I'm so sorry you are going through this. I had similar recently with DC3 - a 1 in 34. Ultrasound looked clear, NT was 1.6mm, but the bloodwork damned me.
I have exactly the same sentiments as you as regards children with Down syndrome, abortion etc. I also desperately needed to know, but I knew I couldn't live with myself if the amnio caused miscarriage. It didn't help either that a lady on a due date group I was on lost her healthy baby as a result of amnio at a top clinic either.
So I went for a late amnio at 32 weeks - the NHS offered this. The risk of miscarriage becomes a risk of preterm labour. DS does not have DS, and best of all I found out before birth but without really risking the baby.
I won't lie - the 20 week wait was horrendous, and I got very obsessive over all the facts and figures, but for me it felt like a good compromise.
A few more things - I believe my bad bloodwork was caused by my bHCG being higher than normal due to first trimester bleeding. IVF or vanishing twins can also cause abnormal bHCG, and of course some people have higher than normal levels naturally anyway.
Low PAPP-A is related to the placenta - mine was crazy low at 0.2MoM which was the main driver behind my bad risk. If your PAPP-A is low (below about 0.4MoM I think) which I suspect it is, you should be offered a growth scan at 28 weeks or so as it can cause growth problems, and there is also an increased risk of pre-eclampsia. Chances are fine all is fine though - I think I was told with my number it was about a 1 in 20 chance of any of these things happening and of course with proper monitoring the risks to the baby and you are not significant even if something does happen.
Frustratingly there's a maternal blood test that will be available in a few years that gives a 99% accurate test for Down syndrome i.e. if it comes back positive, there's a 99% chance the baby has it. If it is negative, there's a 100% chance the baby does not. Which means for those mothers who screen positive for Down syndrome, most will never need an amnio and have to make that particular awful choice. Roll on that day!
Sending you strength - it is a very hard time. I heard so many happy endings even with crazy high odds over the time I was waiting. I could never judge anyone no matter what their choices over these things and how they end up.