Help... Very odd cycle.

I have been tracking ovulation for 2-3 months now using ovulation strips and my Ava bracelet. My cycles are usually 29-34 days long. For the past 2 cycles, I ovulated on CD 21 and CD 17. This time, I have been using ovulation strips since day CD 12 until today and haven't gotten a positive LH test. AF arrived today on CD 19 which means I probably ovulated on CD 7 which would be the day after AF ended. I've never had a shorter cycle than 26 days and that was about a year ago. Any insight as to what might be going on? Why would I ovulate on CD 7? We've been TTC for 3-4 months and can't seem to get our timing right!