I think I understand how you feel.
My DD2 was born with a genetic abnormality which we didn't know anything about until she was born. It was incredibly hard to come to terms with - she had a cleft palate, heart and arterial abnormalities, compromised immune system (missing half her infection-fighting cells) and breathing problems. She was tube fed for ages, she spent much of her first year in hospital with infections, we were told she probably had ovarian cancer at one point and when she had her palate repair she nearly died. The consultant's exact words were: "She's tachycardic, she won't last long like this." Terrifying.
Anyway, my feelings towards her were primarily that I didn't want 'this' baby, like it wasn't the one I'd 'ordered' and I know how dreadful that sounds, I really do. I was terrified of her having the facial features of the syndrome that she has, I was certain I couldn't love her if she did. And she looked v odd at birth. I really struggled to bond with her - and every so often I would experience this deep, raw grief that it had to be my child who was "wrong". All in all I didn't deal with it very well! I would have protected her with my life, but I'm not sure I loved her. (Please bear with me). Every day I would wish I could insert the missing DNA so she would be 'normal'. But to my surprise it really didn't take very long at all before I decided that actually, I wouldn't change her for the world. I still struggled, but I wouldn't have altered her.
Anyway, I put a brave face on it all until other things happened (separation, divorce) and in August last year I was diagnosed with post-natal depression as a result of all this. DD2 will be seven next month. Since my treatment started (anti-d and counselling) I have fallen completely and utterly in love with her. But I have to be honest and say that there was a barrier between us for all those years. Now I feel huge guilt about it and resentment for missing out on her precious early years. I wish I could turn back the clock.
Sorry, this all sounds like a rambling post about me, but my point is that no - you are not unreasonable. Definitely not. Don't ignore how you feel, accept it and talk about it - the alternative could be awful.
I know a few people who had babies born with genetic problems and therefore health conditions - some dealt with it better than others, some cracked up completely - but every single one fell in love with their individual child. It really doesn't take long before you realise that you wouldn't change them for the world. Don't make the mistake I did and miss out on so much. It might be worth pushing for testing, even if there's no medical reason, it would be good to know before he/she is born.
Please don't berate yourself or feel guilty for feeling as you do, it's completely normal and there's a lot of support out there. Xxxxxxx