Angie,
If it has only been a couple of days since you had sex it would be too early to detect whether you are pregnant yet or not. It usually takes about at least ten days to be able to detect the HcG hormone. Usually it is best to test after you have missed a period. If it turns out that you are pregnant I would encourage you to have this child, but I would encourage you to not try to deliberately get pregnant, even if your boyfriend says he wants a baby. There could be a number of reasons why your boyfriend is acting wierd. Perhaps the thought that you might be pregnant has sunk in and is scaring him, perhaps it is something entirely unrelated. I would talk to him and find out what is going on. Good luck.
Kate