40 day cycle

So my cycles are irregular since I’ve been off of bc. They range from 40-46 days. I don’t know my exact ovulation but I thought I had a good idea. We have been able to BD every other day for the most part. I took an ovulation test a week ago and got an ALMOST positive, the next few days the lines were barely there and obvious negatives. Does anyone else have a long cycle? If so, around what day do you ovulate? AF isn’t due until Feb 18th according to glow but I’ve been having bad cramps and my lower back is so sore, which isn’t normal for me because I’m very active. Could I have already ovulated and conceived? Or can I ovulate twice? Seems silly for me to take a HCG test because AF isnt due for another 3 weeks according to glow.