Help! I have a 2 year old and a 4 year old both conceived on the pill, so I went onto a different type of contraception after our second and now we’re trying for baby number 3.

It seems the new contraception was very effective as 7 months off it still nothing. I knew it would probably take a while but I’d like to test to see if I even am ovulating yet but I have no idea where to start. What tests should I buy? When do I start testing? How do I know if its positive etc.? Thank you in advance 😀