Pre-seed question...

When it comes to AF, they are irregular periods at that! So I really don't know when I'm ovulating. I try to keep track bu checking my CM but it's not a regular thing. So I've seen a lot of positive reviews on pre-seed and want to give it a try. We have been ttc for 3 years already!!! Is it ok to use pre-seed EVERYTIME we BD or when I'm just ovulating??? (Again not so sure when I ovulate)... Also what is the amount used? Personal experience are more than welcomed and greatly appreciated ... Thank you in advance 🖤