OP, we don't know your DH so it's impossible to know if he's a borderline abusive sex pest or a loving husband who fears he may lose you for good unless he can kickstart your love life again. Doesn't matter what we think anyway, what you think is what counts.
Are you able to get a babysitter? If so, I'd recommend going out for a meal. But if that's not an option, maybe try an M&S Dine in for Two meal or something. What you need is an activity where you can sit down and focus exclusively on each other but in a non-confrontational way with the opportunity to take a minute to think before speaking (by looking at your plate, chewing on food, drinking wine etc). If you can do this out, so much the better, because it will keep both of you on best behaviour, but it's not vital.
You need a full and frank discussion about this. It all needs to come out. Neither one of you is a mind reader and human beings are great at wildly misinterpreting each other's behaviour when emotions are involved. The only way to counteract this is honesty.
I'd sit him down and say you don't feel like sex at all. Tell him you are really sorry if that makes him feel rejected because you love him and don't want him to feel like that, but if you force yourself to go through the motions you will kill your marriage because you will come to resent him. Tell him this is why you reject his affection - because you are scared it will lead to a situation where you have to reject him which will simply leave both of you feeling like shit. Tell him that you don't want to feel like this but that you need his help to resolve it.
Tell him that to resolve it, you need to establish where it is coming from. Then talk to him about the fact that you've lost your friends and family and feel isolated. You had a traumatic birth that you've not yet come to terms with and you're struggling to adjust to life as a mum because you don't have the support from family and friends because you're so isolated. Explain that right now you feel like an exhausted struggling mother whose lost her life and her identity, not a carefree woman with a life of her own who embraces life and love and can express it physically through sex.
Then tell him how you want to recapture those feelings. That may mean him having your child more so you can go out to a gym class or take up some sort of hobby just for you - something that is unconnected to your DH or your DD. Maybe think about returning to work. Think about something you can do with your DH that is fun but can't possibly lead to sex because it is out of the home environment and suggest doing that. Say you need to recapture the sense of fun and adventure in your own life in particular but your relationship as well, and that if you can do that you will probably find your libido returning. Happy, vibrant people have more sex.
The listen to his response. If he gets defensive, tries to blame you in any way, thinks you "need to get over it" or that he already does everything he can and you should make more of an effort for him, you have your answer as to whether he's an abusive sex pest or a frustrated-but-loving husband. If he says he understands, agrees to back off and helps plan your solution to this, he's a good DH.
Hope you get things back on track.