Look I'm going to go against the grain but honestly I would have the amino done.
My first darling boy was born still. I went on to have a healthy DD and my second son and he had the odds of 1:4 for Edward's syndrome. Since the life expectancy is very different from downs you may say if he has downs it doesn't matter but I would argue it does.
If he does have downs and you decide to go through with the pregnancy forward is forarmed.
Thankfully my son doesn't have Edward (confirmed via amino) but he did have a v serious heart condition that since we had had the amino and various heart checks was picked up in utero so managed his condition as soon as he got here. If it had been a surprise I don't know if he would have made it.
The wait for the results left like years. Bloody years. But there peace of mind helped me know there battle I was facing.
And let me tell you having your first baby is like going to war, you won't win if you have your eyes shut going lakala. It's amazing but brutal I'm so many ways.
It's your body, do the amino if you want to, the risks are really v low (obviously not 0) but in our case it saved a life not risked it. Not that at the time I wasn't bricking myself.
The amino will tell you defiantly yes or no. I believe there's a test called the harmony test that also pretty definitive and that's just blood work but nhs won't do it and you have to pay for it privately. It's not peanuts either.
No matter what you chose, the deck is already so to speak stacked. It won't do you any good not looking at your hand and playing blind.
Good luck and ps GB sucks arse but pretty common. Don't beat yourself up here. Your doing a good job. It will be worth it in the end.
And if your wondering if the worrying about the baby will go away. It doesn't and they have the audacity to leave the womb and venture out into the world. So the worry changes rather than vanishes.
But you aren't alone if it helps. Mums worrying about their babies/children/adult children keeps the word spinning.
I hope whatever the outcome you fine peace 💐