Irregular cycle and TTC, help!

Katie • Married, mom to three beautiful girls. Nori - 12/23/2009 Ashtyn - 4/16/2012 Emerson - 8/4/2015
I've been trying to conceive #3, but my cycle is so irregular. It can be anywhere from 28-40 days. My first two were both unplanned so I feel completely lost now that I'm tracking. I've taken an ovulation test every day since the 19th of November (4 days after my period ended) and they've all been positive! That seems like way too long of an ovulation time frame? I feel so lost. I started using a basal thermometer. And my readings keep going up by .1 - .4 over the last few days with today being 97.90. I feel so confused with all of this. Does anyone  have any advice or same situation?