Ovulation MIA

Chelsea
I have been taking OPKs each morning for a week. The package said I should start taking them on cycle day 15 because my cycle is 30-32 days long. I am now on cycle day 21 with no surge.
Last month was the first month I used OPKs and I got a positive on cycle day 18. 
I have been tracking BBT and CM since May as part of the sympto-thermal NFP method. I was on the pill prior to that.  And my peak day has always been day 20 since off the pill. 
I also started having possible UTI symptoms yesterday and took Cystex for them. Not sure if that can affect it.
Anyone have similar things happen or have any thoughts on what may be happening?