Confused

I know this is going to sound awful...but my fiancé & I were not together that long after I found out I was pregnant (4 months) when we first got together, it was amazing & very passionate. Of course that fades away in time sometimes. Here's my problem..I moved states with him & found a really good job & have started a program in school to work at a pharmacy..I don't see our relationship going any further though. I don't see us getting married anymore & honestly can't even really see us being together forever as much as I want to. We're both really young, I'm 20 he's 22. We still have a loving relationship a lot of the time but this feeling of not working out is always in my mind. & I'm so scared of it not working because if it didn't, I wouldn't want to quit my good job & drop out of school to move back home. I would definitely struggle as a single parent. I have my daughter in December & don't quite know what to do.