I’m so sorry for your loss and the fact that you will have to deal with your sister’s pregnancy. The first thing I will say is, look after your heart and don’t do anything that makes you feel uncomfortable. Don’t force yourself to go to her baby showers, or look at her scan pictures, or rub her belly. Just don’t. There are no prizes for being normal and bubbly.
You need to speak to your sister, and your family and explain that you are really struggling with her pregnancy, you wish her the best and you wish you could be there for her right away- but you just can’t. Unless your family are thick and selfish, they will understand. But get this out in the open quickly.
I know how you feel. With my first miscarriage, just as I was getting better, a girl in our social circle (girlfriend of my DH’s close friend) announced they were having a baby. This was whilst I was in the throes of acupuncture and temperature checking and trying to get my cycle back on track. It hurt so much. I got pregnant again just before a big gathering and thought I’d be strong enough to see them, but then miscarried again just before.
All I could think was ‘I should be more pregnant than you’ and it turned me into a bitter, angry person. It was such a horrible time in my life. (I didn’t even have the joy of being happy for them as the woman had moaned a few months before about her boyfriend not committing to her, then BAM surprise ‘I was on the pill’ baby 😂). Those ugly feelings were absolutely toxic and ‘being normal’ just supercharged them. I had to stay away- for everyone’s well-being.
Look after yourself, exercise, meet friends, do hobbies, start hobbies, book a nice holiday or getaway if you can afford it. Chasing NHS referrals or going to see a private gynaecologist to get some suggestions of things to try next pregnancy might make you feel a bit more positive going forward. I’m sorry if that sound simplistic, I hated people telling me these things but now I realise it was so important to look after myself and my other needs.
Thankfully I caught the next cycle, got a progesterone prescription and I am currently snuggled up with my new daughter.
best of luck to you. Xx