Thank you @SnookyPook, congratulations to you too. I'm glad things are going well for you. It's so hard right now, but I know I can't control things by worrying. I am actually seeing a counsellor through the local health visiting postnatal team, but she's been on holiday so I haven't been able to connect with her since mid December. But I know she'd tell me to focus on the fact that it's up to my body and no amount of testing will change anything.
@warmbutteredtoast thank you for sharing your experience. I've just had a calming thought which is that I do have a wonderful little boy and my family are fine as we are, even if this foesnt work out (I hope it will obviously). I will try to keep that in my mind and try to stop testing (I have 2 more....)