Hi! I'm of a really similar age and can relate to your girlfriend on some level because I've felt that way too at some point. I don't think you should feel guilty because it's clear from what you've said that her feeling this way is possibly due to some miscommunication.
Reading through some of the comments, I support what you want to do! When you see her tomorrow, the best way to go forward would to just be honest about what you've been going through lately (which I hope isn't causing you too much stress and you're okay). Also tell her how you feel about her :)
You seem like a really sweet and genuine guy so I'm sure that she's just as much so, and I'm positive she'd be very understanding about the situation.
Maybe you two could plan a fun date together or surprise her with something small but sweet, like getting her some flowers (or even just one). There doesn't need to be much money spent or anything extravagant planned. It seems like she just wants to connect with you a little more and be reassured that you care about her.
I hope this was at least slightly helpful and everything goes well tomorrow!