When would you test?

[WishingForTheImpossible]

My periods for the last 2 months have been a bit erratic, I'll start bleeding for 4-5 days, then it stops for a couple of days and then starts for another 3 days. This month it was the 3rd-15th October.
Because they are all over the place and I'm about to turn 39 we decided to start ovulation testing to try and increase our chances of conception.

I started ovulation testing the 16th.
Every day the reading is the same, not getting any darker or showing ovulation.

We are however having sex regularly, most days, but during my period every other day.
Last night I noticed a small amount of watery blood after sex, I've just been to the loo, wiped and there is more watery red blood.
Could this really be implant bleeding??
If so, when would you test? As I have no idea when my 10 days post ovulation is

If first day of cycle is 3rd October then based on a typical cycle you’d have ovulated around the 17th October, so I’d test at around 31st October if no period has shown.

The only other thing I’d mention is I know some of the symptoms could be perimenopause, periods suddenly becoming a bit odd, no positive ovulation test, and bleeding after sex can all be signs, but of course it may be nothing like that at all.

Even with your periods the way they are I’d just take it as day 1 is 3rd October so 4 weeks roughly from that to test x

Thank you @Mrsttcno1
This is the first month since we started in May that I am feeling hopeful, I suspect the next 9 days will be exceptionally slow!