@Daffodil21 I've been using One Step internet cheapies and they've been stark white negative.
I'm not hopeful because I had really sore boobs from 5dpo until 11dpo and now they don't hurt anymore, which is what normally happens for me the day before AF. (apparently it's due to Progesterone dip?). I was expecting AF yesterday as it normally arrives bang on 12dpo. I didn't use OPKs though so maybe I ovulated later than I thought, although I got pretty strong ovulation cramping on the day which I estimated was ovulation.
Still getting the dark brown stringy discharge but (TMI) it's only when I check 'inside'. When I wipe normally there's barely anything on the tissue. I did some research and apparently dark brown discharge means old blood. I hardly ever get brown discharge or if I do - it's more like brown blood and only lasts a couple hours rather than this weird stringy stuff which I've had for over a day now!