Overactive Imagination Working Overtime

Hi. i'm fairly young, 21. I'm a single mom, full-time college student, and I work at a gas station as well. OK. I have a lot of responisbility and other stuff on my plate. I was in a bad relationship for about three years, and have been single and healing for approx. two years. My major in school is a pretty time-consuming one, and most of my spare time is spent with my son or at work. I do go out with friends about once a week for a couple of hours. As it is, I don't have time for a relationship at the moment. I don't think I'm emotionally stable enough anyway. My ex messed me up pretty bad. THAT is beside the point. I have the next several years tentatively mapped out for my son and I. You know, finish shchool, start my career, him start school, move a couple times for school and career. OK. I somehow conveniently forgot to leave room for a "man" in my life. That is ok, because my priorities are where they need to be at the moment. BUT, I don't want them to be so set that I end up being a 40-year ld single parent of 1. I want more children in the future, but I'm just not ready for a relationship. I know it's ok to be single, and it's the most sensical thing for me right now, but what happens if I get set in my ways and I can't get out of my "funk" and back into the field?? I know it's my imagination working overtime(i hope), but any thoughts anyway??