Hey! I'm also 28 weeks pregnant, congratulations on being constantly kicked in the bladder! 
This is my second DS with DH.
I fell pregnant at 19, at the time, me and DH were 'friends with benefits' and had been since we were 15! We'd never been in a relationship, we were just best friends who loved and cared for each other, and had sex quite frequently 
When I found out I was pregnant, he was actually in a relationship with another girl and although he ended that, it wasn't really because of me. I'd love to say he dropped everything to be at my side, but he totally freaked out.
The minute he held his son for the first time, he was hooked. It was like all those years of use denying just how much we loved each other vanished. He moved in with me, and was the most amazing Dad in the world. He still is! We got married a year later, and are still madly in love and crazy supportive of one another.
That's the most important thing about raising a child, it's not 'how ready you are personally for a baby', but how ready your relationship is.
You and your DP already seem to have better communication than most the women on mumsnet. That's a HUGE positive!
Keep this up, keep talking about your feelings, keep laughing with one another. Have date nights where you don't talk about the baby, and plan date nights where all you do, is talk about the baby!
You're 28 weeks, you have time to think about adoption, if that's something you really want. But keep communicating. Talk about why you don't feel ready, and try and combat those fears.
I read a stupid, and cringe worth quote a while back, but it's really helped my anxiety over parenting. Basically, 'Parenting is the hardest, yet most simple task to do. It's like pushing a 20 tonne Boulder up a very steep hill.'
I took that to mean that, although parenting is super super difficult at times, it's also something that comes naturally and if you give it time.
Hope my 1am rambling helped in some way! Good Luck OP 

