First I have to say.. GREAT JOB!
I am 22, single mom, going to school half time and working almost full time (can't get quite enough hours to be considered full as of now). I live under my parents roof, but we pay separate bills, we buy our food separately, and I provide everything that my daughter has. No child support (let alone contact from the idiot "sperm donor" as I like to call him), and no help from others except for babysitting when I work (I work nights so that I can have family help babysit). I know how extremely hard it can be. I had been going to school full time as well, and realized after falling behind for the first time last semester that I had to take it slow. So, I definitely know the feeling.
My absolute best advice for you is something that my mother taught me when she went back to school (I was in 1st grade at the time, but I'll never forget)-- It doesn't matter if you "stay on track" to graduate. Or if you are a full time, part time or half time student through the whole thing. What matters is that you eventually get there, that you understand what you just paid to learn, that you can use that knowledge, and that you didn't miss anything that happened in your own family. Family will always come first."
I am taking that advice to heart now, and feel like it has definitely saved my sanity for the past year (I actually sat in my hospital room almost a year ago, right after having a cesarean, and tried to submit homework assignments.. thats when I realized that I needed to slow down a little).
Good luck, and great job in setting a great example for your little one! I have the same outlook that you do, it seems, and hope for your sake that you aren't over-doing it. Remember.. you can reduce the number of classes you are taking. You can even come back to them later. But you can never get back the time spent while your baby is busy growing up. There is no rewind button there. Enjoy it while it lasts, because soon, they will be doing the same thing with a family of their own.