Sorry Lucy, I didn't mean to panic you.
From the reading I've been doing I think it's quite normal that we don't ovulate each cycle.
If you're periods are light normally then it doesn't mean that you're not ovulating. For me it was very unusual to have just a 3 day period of brown discharge but I don't have heavy periods as a rule either.
Defo give temping and the OV sticks a go, it will help you find out exactly what's happening with your cycle. For me it makes me feel better because I feel that I'm doing something to help me conceive - I'm not really but it's all in the mind isn't it?!