help help help

My boyfriend and I have been dating for a few months now, there is an age difference. I'm 18 and he's 23. He's talking about marrying me and starting a family together... but idk if I'm ready for all of that. We already had a pregnancy scare (I ended up not being pregnant) and he's talking about getting engaged by Christmas time... what do I do? What would you guys do in this situation ????