opinions please!

Shannon
Hi all. Having a hard time this week and I'm looking for some input!
I don't have a typical normal cycle, but in the last 8 months, I've been between 34 and 36 days long with one 39 day.  Right now I'm on cycle day 42. I have had slight cramps for a couple hours two days ago but that was it. Slight spotting (brown) but I usually don't spot like that before AF. But no other indications of pregnancy or AF. I've gotten 3 BFNs, most recently on CD 40. 
I haven't been able to pinpoint ovulation dates with a first response kit, I'm assuming I ovulate later than normal and ran out of test strips before I ovulated (they only give 20.) I'm assuming I'm currently somewhere around 20-21 DPO and I'm around 3-7 days "late" for AF.
I'm super frustrated, so are there any suggestions as to what to do next? Has anyone ever gotten a BFP this late after multiple clear BFNs?  Can anyone with irregular cycles send some encouraging words? When did you reach out to your dr for testing and help conceiving? I'm trying to not overthink this, I've pretty much counted myself out for this month for a bfp but I am getting so disheartened.