Should I move in with my babies dad?

so I have a son with a good guy, awhile back our relationship was not so good 3 months after I was pregnant we broke up. He is being a way better father then he was 4 months ago. Every weekend I go up there to let him see the baby, He is currently living with his parents. They love the baby and me to death. we get a long great as well with my mom. he has two other children he doesn't get to see and this is his only boy. we were psyched. His parents want us to get married (but in our own time) I have been trying to find work to support our son. I told him once my GED cles are over and IF I find work up there I will move in. Last night I told him I want to work things out. I told him I wanted to be engaged. So we are together again. But now I am confused if I want to be with him or not. i told him I can change my mind anytime I want and we can still be friends and he said that whatever I decide we will do. He really really wants to be with me. And if I tell him no I want to wait a little longer I don't want to hurt his feelings, plus he told him mom last night, so she probably is stoked about the whole thing. I am really confused. why am I all of a sudden feeling like this? does it mean I don't really want to marry him? please help. I leave for the weekend tomorrow afternoon. and i need some way of telling him If I do decide not to be with him. Oh yeah his mom and dad and him live in a 3 bedroom house, and when I go up there I sleep in one room with the baby and he sleeps in another. we are not having so biblically we can be seperated. I told him since I don't know who or if you slept with anyone you are getting an std check before we do. I get the depo shop on the 27 of this month. does the shot work? thanks and GOD bless