Hi Millie, I was going to ask what stage you're at but if you're still a week til otd then it's definitely too early to test. Fingers crossed for you.
I tested this morning with a frer, says you're supposed to read it after 3 mins then discard after 10. I think I read it after 2-3 mins, negative so I went back to bed. Looked at it again when I got up 20 mins later and there was the faintest of faint faint lines there. A proper "hold it up to the light and squint", I can't even see what colour it is so I'm going to assume evap. I think I may just go to the doctors later and ask them to do a blood test, they're very good about stuff like that here.
Just to update on this, bloods came back at 6.3 so almost certainly a chemical.