is there a test that shows if you are able to ovulate?

Melanie
Hi there!
I'm 41 and my husband and I are trying to have #3. Our sons are 5,5 and 7 years old. We started trying for #3 in juli last year. 
I thought we didn't hit the right day so far, but I started to wonder and took OPK the last two cycles. They turned positive and I also started BBT this month, but my temprature didn't rise.
Do you know, if there's a test for Ovulation in general? To show if there's still a chance for an Ovulation?
Thanks so much!