confusing cycles after miscarriage

[Southerngal32]

Am hoping some of you may have some advice!
I am ttc no2, I have a 3 year old.
I had a miscarriage at 11 weeks last November, we waited for af to come back before trying again.
However the last 2 cycles I've bled for 13 days out of a 28 day cycle. I have got some opks to try this month. Last month im sure I had ewcm on day 23 and then af started a week later.
I'm obviously concerned that either I'm ovulating really late so no chance of maintaining a pregnancy or I'm not ovulating at all! I realise it's probably too early to be concerned yet, hence I haven't rushed to my gp but I'm also conscious that I'm in my late 30s so time may not be on my side!
I desperately want baby no 2, any words of wisdom?