First off, I think you miscounted the number of parks. There's 4, not 3. You'll have enough time to hit them all. Hollywood is a half-day for sure. Animal Kingdom could be a half day, but could be a full day depending on what you make of it. Even Epcot could be a half-day if you're trying (I wouldn't recommend that though).
Just how frugal are we trying to be? I'm going to tell you how to save money, as well as all of the reasons why you shouldn't. :)
Depending on how you like to spend your vacations, there's value in NOT going into the parks for one day. Some people (not me) like to resort-hop, spend time at the pools, relax, etc., etc. You could make an entire day by doing Resort Breakfast, Disney Springs, Resort/Springs Lunch, Resort(s) Pools, Resort Dinner, more pools in the evenings.. A lot of resorts will do events such as movie nights that you can take advantage of on this evening too. Resorts are free to get into. Again - this is all your and your bf preferences. Personally, I'd rather be in the parks. However, you could potentially save a park ticket this way. We always do a dinner or two at a resort on our busier days just to get the break and see other parts of Disney.
You could stay at an off-site hotel for cheaper... But...
Are you flying or driving? If flying, fly into MCO and take the Disney Magical Express to your Disney Resort, utilize the Disney provided transportation all week, and take the Magical Express back to the airport, and not have to worry about driving the whole time you're there. Immerse yourself into Disney for 5 days. The convenience is worth any extra cost. If you're driving, then you could want to look at off-site hotels, but now you're on your own to get to the parks and find a parking spot vs being dropped off and picked up next to the park entrance and not moving your vehicle for 5 days. Depending on your decision with the meal plan, a hotel with free breakfast might be a good choice (pack those apples/bananas/muffins for the go!)
It is possible for you to spend less money on food without the meal plan - eating outside the parks at "normal" restaurants, utilizing breakfast at your hotel if off-site, and such. However, you absolutely will not be able to eat the same quality of food for that price. And eating at the Disney restaurants will be equivalent to your meal plan halfway into your trip (I did the math on our last trip, paying for food would've been double the cost). And the magical experience that Disney provides is included in the restaurants. The basic meal plan is 1 snack, 1 quick-service, and 1 table-service. Quick service meals are like 5-star fast food. I always compare them as Chick-fil-a vs McDonalds for a sandwich - but better. Plus you'll get a side, drink, AND dessert with your meal. Think fries as a side and a cupcake or parfait or ice cream sandwich as a dessert. Table service meals are going to be $25-30 steaks kind of meals, and again desserts are included. So have your cake and eat it too. ALSO. Do not, do not use your snack for a bottle of water. Get that pretzel/ice cream instead. Every park has a Starbucks (it'll have a different name, like Main Street Bakery in MK) that will give you a free glass of ice water. Not sure if this works at all the quick service places or not. Try it and let me know. I always get a Large (or Venti) sized ice water and my wife and I share it. But we each could go through and get our own if we were really thirsty. Two Disney meals will be enough to get you through the day, esp with a giant pretzel as a snack. We almost always have snacks leftover at the end of the week because we didn't need them. Then we stock up on cookies from the gift shop (candies under $5 can use a snack instead of purchasing). Pack pop-tarts or granola/Cliff/power bar type things to eat as a quick breakfast when we leave the room in the morning if you're worried about it or you're just used to eating breakfast first thing regularly. Also - get reservations for table service. You can do it 180 days in advance, you're already behind.
Other advice:
Unless you're packing food (which you won't be, cause you're doing the meal plan, right?), and it's just going to be the two of you, I recommend buying one of those phone cases or wrist wallets that you can slip an ID into and maybe a credit card with your phone for those just in case emergencies. If staying in the resorts, you can use your Magic Band to charge to whatever card you've put the resort room onto. And the gift shops will even deliver to your room so you don't have to carry bags around (not sure about Disney Springs on this, someone else here can I'm sure verify that). However, I always feel better knowing that in the rare case of a really bad emergency, I'll have access to money no matter what. And you won't have to carry around a bunch of stuff all day either. It's quality time with the man right? You don't need the phone.
Now to convince you to spend more money...
Speaking of the phone, I also recommend getting the Memory Maker. It's also worth the cost. There are tons of cast members standing around to take pictures. They aren't professional photographers, per se, but they are trained to take these pictures with the characters and/or iconic background. Then they swipe your magic band, and on you go. Most of them will take a cell phone pic too if you ask, but they are available online in a couple of minutes. Also, pictures from your rides will automagically populate into you Memory Maker account, so no standing and waiting and purchasing ride pictures either. You can choose to not do this in order to save $150. But not having to carry your camera. If you do this, make sure you get as many of those pictures as possible to make it worth it. You should be able to easily get 10-15 pics per day - between rides, characters, and then just the cast members standing around.. On Main Street in MK, between the gate and the castle are at least 5, sometimes more cast members waiting to take your picture with the castle in the background. Every iconic thing in Disney has one or more of these cast members whose sole job is to do exactly this.