Scared - Pre•Pregnancy

I am a soon to be mom, I am a senior in high school with a boyfriend in the military ( who is the dad) . My boyfriend is gone for training during the summer. He’s the one that always reminds me how good of a mom I’m gonna be and all the stuff, but lately I feel so disconnected from my pregnancy because of thoughts that, I’m not ready, so how am I gonna be a good mom? What if I let my baby down? Stuff like that. I was really excited, and deep down I am but lately all the scary stuff has taken over again . I guess I really don’t know why I’m posting this, to see if anyone’s else gone through this, what I should do, how I can feel closer to my baby again, anything honestly would help.