Hi,
I'm sorry to hear you are going through this, I am feeling exactly the same way and it's awful. I'm 30 weeks currently and all of my check ups etc have been fine and my pregnancy has been fairly easy physically (so far) but my anxiety has been hell.
I'm totally obsessed with monitoring the baby's movements (having an anterior placenta doesn't help!) And have been in 3 times for reduced movements when I didn't feel anything for hours and none of the tricks to get them moving were working. Everything has always been fine but I still get worried when I go a while without feeling anything. With my placenta, some days I feel movements easily and others I feel barely anything so even now I don't really feel like I have a baseline for what's normal for my baby. Always go get checked if you are really worried, even if you've been in a million times. The midwives never mind and it's better than sitting at home and stressing yourself out.
I've had two sessions with the mental health nurse at my hospital and it is helpful to talk to someone about it but at the end of the day they can't take away the anxiety and fear. They have given me some tips to try and stop myself catastrophising all the time and it has helped a little but I've just had to accept that I'm going to be anxious about movements until baby is safely in my arms and that's ok.
Even though no one can guarantee any outcome with a pregnancy it does help to remind myself that there's a 90+% chance that everything will be ok and most of my anxiety is my brain trying to protect myself from something awful that has no guarantee of happening.
I still struggle to get excited about the baby being here because I'm so terrified of the alternative but I have started to buy some baby bits and bobs in the last week or so which I wasn't able to do beforehand.
Please know you're not alone, anxiety is so common in pregnancy and so many women go through it.
I've found some CBT techniques to be helpful in managing my anxiety a little, and I've heard others say hypno birthing videos on YouTube have helped them to be more in the present instead of spiralling about what ifs, but I haven't tried those yet.