Birth control/ breastfeeding/ fertility awareness!! Help

Ye
Question: what will you be using as a birth control? I'am breastfeeding and I know some BC tend to decrease milk supply... The only one I've heard is ok while breastfeeding is the mini pill. I've tried many BC options and they all get me moody, very depressed, and anxious. It seems like the only one that worked for me was the IUD without horomones. The thing is that that BC method is for 10 years and I plan to have my 4th baby in 2 years. The only thing left is fertility awareness...has anyone used this method before and is it effective? I'm catholic but have not been able to confess do to the BC I was in. Therefore, I'm really looking forward to the natural way of fertility awareness... I'm just concerned it won't be as effective. What do u think?