I (17F) and my bf (20M) I love him and want to be with him but something is not working between us

We have being dating for the last 5 years and we love each other and mostly we were in long distance he used to ask me for nudes and at the beginning I shared but I was never ok with it I thought maybe with time he will understand and he will stop asking it recently we got intimated and then now he wants to do it again but I'm scared of being pregnant. So he agreed with me but now my problem is that after all this now that I ask him to not ask about nudes and not to get intimate he started behaviour weird he doesn't show any emotion towards me and we mostly text each other so I don't know what should I do. Any suggestion??