I think, just going by how you described your life/situation right now that you are just looking to fill a void that your ex left. I don't advise trying to get pregnant just to fill that void, having a baby just so you can have someone to love you & to have something to remember your ex by is kinda wrong. It would be alot better if you waited until you were out of college & could better handle a baby.
And yes, babies love you unconditionally but they are very very hard work. How would you do college with a newborn that wakes up every 2 hours? You have to think of it frmo a financial standpoint too - can you afford diapers, clothes, a crip/bassinet, formula, car seat? Do you have a room for the baby to stay in? How would you balance school with taking care of a baby - would a family member babysit, or would you have to put him/er in daycare [which is pretty expensive]. Would your ex want to be in the baby's life - it's hard growing up without a father.
I'm not trying to be mean but you really gotta think before taking a HUGE step like this.
Maybe try talking to your ex & telling him your feelings towards him, maybe you can get back together with him without having a baby? I know the heartache you're describing & it hurts & it's hard but you need to either talk to your ex & see if you guys can work things out or just let him go & get on with your life. He might have seemed like your first love but there are many great guys out there, ones who will stick around, marry you & give you lots of babies if that's what you want.
Good luck ♥