How to be excited during first trimester?

I'm 6 weeks pregnant with my first after being diagnosed with unexplained infertility a couple years ago. I wasn't trying to get pregnant and having a baby is something I definitely gave up on.

I feel guilty because my boyfriend is really excited but I don't even want to talk about the baby or make plans or pick out names or anything. I feel like it isn't real or I will just end up miscarrying.

I don't want to be in such a negative mindset. I want to feel happy and excited because I know I should. I know this baby is a blessing and a miracle but I also don't want to get my hopes up. Does anyone have any advice or been through something similar?