I know you asked this question 11 hours ago, but I'm going to answer and hope you read. Often times I find I write long responses on here and they're rarely acknowledged.
Be realistic. You can't have your cake and eat it two. It's impossible to be a stay-at-home mom and a working psychologist (or go to school) at the same time. So, you are going to have to choose one or the other. Are you willing to give up family time (ie. have a babysitter) in lieu of working in a field that you may not even like once you find out how things are? You can go to school and be a mom--just not a stay at home mom.
Do the math. It takes 3-4 years to finish a masters degree. You can only apply once a year (usually September/October). So realistically you will miss the date and have to wait until 2017 to apply. If you're 22 now, you'll graduate by the time you're 26 if you don't lag behind. Say you get pregnant right after graduation, when you're 27. If you want to start working when you're 30 you've already wasted 3 years of being out of work. What have you missed? Have you missed any new procedures/methods/etc.?
Are you sure you want to get your masters? If you're adament about going to school to get your masters, then never let money be the reason you don't go. There are scholarships and student loans. Yes, you will go into debt. But for a field you love, sometimes it's worth it.
Here comes the wake up call.
I have my masters in clinical psychology (I'm verified on /r/psychology). I graduated with a 3.94 GPA. I worked harder than I ever worked on anything. I don't have kids. You have to take your GRE's before going to grad school. Most decent colleges (not talking about Ivy league colleges) only select 20 or less students for the masters programs. There are typically 500+ applicants. So you need outstanding GRE scores. In addition you need a pretty decent undergrad GPA. I'd say anything under 3.5 will probably get pushed to the side. Sometimes they pick below those GPA's but it's typically when outstanding GRE scores overshadow them. If you took a lot of research classes and a lot of statistics classes as an undergrad, in combination with a high GPA and GRE scores, you're a shoe in. If you do make it in, be prepared for clinicals that will suck the soul out of your body. Be prepared to not sleep. Be prepared to do more work than you ever have. Be prepared to have your mind made of mush. There's no online for this, so if you're used to online classes, you're screwed. This takes discipline. If have further questions about being a psychology grad student, please go here: /r/AcademicPsychology/
Learn to love debt. I owe $110k in student loans. But if the thought of that makes you cringe, you ain't heard nothin yet. I loved every second of grad school. Ever hard ass damn second. I thrive in stressful situations and it's the most stressful thing I've ever went through. But I hit a wall. You see, life in all of it's oh so unpredictable glory threw me the most fucked up screw ball I've ever had the displeasure of fumbling to try to catch. After I graduated my body decided to say, "Oh hell no you aren't." I was hit with a multiple sclerosis and RSD bombshell all at once. And now, I barely walk. And when I do walk I'm in so much pain I pray to pass out from it. I refuse to take opiates because they're addictive, so I sit and suffer. I miss working, I miss utilizing what I've learned. So, now I get to pay back all of those loans and I can't even practice. The only way that I'm lucky is that my husband makes $200k a year. If he didn't I'd be fucked. So. Ask yourself---are you prepared to be in the same boat with less money (from what you've said)? Because if you aren't, and you love what you're doing now---then do what you're doing now. You don't need a masters degree. You also don't have to choose. You can have a family and work. You can get pregnant right now, and still keep working and not have to worry about a debt to a college. But before you get pregnant, make sure you're relationship is stable enough for it. If you're arguing about money---now isn't the time for babies. Continue with a job you love (if you love it), move up the ladder, and get raises the old fashioned way. Perseverance and dedication pay off.
Oh, for the record---my husband is nearly illiterate because he's dyslexic. If he can make what he makes a year, anyone can. It just takes hard work. He works in oil, it's dangerous and he risks his life every single day, but he loves what he does more than anything and wouldn't ever give it up. He works in 100+ degree heat, and he works in -40 degree cold. You can do anything you set your minds to. It is your life, isn't it? Don't be a slave to anything when you don't have to be.