I've been where you are OP. I'm so sorry this has happened to you... It's such a tough introduction to pregnancy and parenthood. You just don't think it can happen after 12 weeks when it's your first, and the grief is unbearable.
I found out we'd lost the baby when we went for our 20-week scan. She had actually passed away at 15 weeks. As a result we couldn't bring ourselves to ask to see her when she was born, we were too scared of what she might look like... I'm really glad you were able to see your daughter. I sometimes wish I had been braver.
We found the post-mortem results took forever to come back. It was an agonising wait and in the meantime we just kept going one day at a time. I found I couldn't talk to anyone about it except my husband and a therapist (who really helped me come to terms with my grief). Like you I couldn't bear the thought of being around my pregnant friends and avoided them studiously - one of them announced her pregnancy a few weeks after our loss and I was devastated for days. I felt like the worst friend for not being able to be happy for her, I just sent her a quick text then took months to get in touch again... It's really tough and I feel for you, there is no easy way to deal with it, you just have to allow yourself to grieve in your own way.
Personally I couldn't bear the thought of getting to my due date without being pregnant again, and my husband felt ready to try again too so we tried again straight away and I got pregnant immediately. When we went to the post-mortem appointment with the consultant I was already pregnant... There was nothing wrong with the baby we had lost, or with the placenta, which in a way was good news as it meant there was nothing stopping us from having a normal pregnancy next time around. We'll never know why we lost her though and sometimes it feels pretty unfair, but there is nothing we can do about it.
The second pregnancy was highly stressful, we were terrified of another loss and I watched everything I was doing and eating just in case. It didn't help that I had quite a lot of bleeding in the early weeks, thankfully it was only a hematoma and the pregnancy continued. I had to deal with my family's anxiety too, which was quite a bit of added stress... We had a lot of reassurance scans and appointments. When my son was born overdue and completely healthy it was the best feeling in the world. Having him has helped us further with our grief. If we hadn't lost his sister, we wouldn't have him, and we just can't imagine life without him.
I had a very early miscarriage since and am now 27 weeks pregnant with another little girl... This pregnancy has been much more relaxed. We don't have all the reassurance appointments but that's a good thing, and I don't feel the need to regiment my every little intake of caffeine or whatever.
I know all this feels a long way away for you because you're in the thick of it but as previous posters have said, it does get better. I really hope your next pregnancy will be as boring as can be and you'll be able to give your child a cuddle. In the meantime look after yourself and just do what you need to do, there's no right or wrong way to handle such a loss... 