BlueRose
One way I always knew when I was ovulating --- I would feel slight pain in either the left or right ovary. On rare occasions, it would be in both ovaries :)!
You don't say just how much over 35 you are but after a while it gets to the point where you don't ovulate every month. Plus your cycles become more irregular.
Generally speaking, if you are regular like clockwork, then ovulation happens during the middle of your cycle.
If you are trying to get pregnant, then perhaps it would be to your advantage to monitor your temperature. They say the older we get, the harder it is to conceive. However, there are always exceptions to every rule.