Frog, sorry you are in this position and that it feels so impossible. I think I would not have the amnio, in your case, but of course if I was really in your position I would probably be paralysed by indecision. I think 1:140 is not bad, still heavily against the likelihood of downs.
ION, I have just had an initial phone call with an independent midwife. Waiting for her to send her packages/pricing info, but it was a good first chat - the things which surprised me were (a) she takes over A/N care completely from the NHS, so it is like going private, but with referrals to NHS for scans, bloods, etc (b) she only takes on 2 women due per month - the more I think of that though the less I like it, because even if she also assists other IMs at births, it is a low throughput and so does she really get to see and recognise lots of conditions that could present into problems? How many women per month did Domino scheme/case loading midwives from NHS trusts typically handle, when those schemes existed?