Diaphragm? Anyone got experience with one?

I'm running out of birth control options (cannot take combined hormone based contraception as I suffer migraines and it increases the stroke/blotclot risk - also recently had the implanon/nexplanon removed as it was giving me very negative side effects)
One of my only options is using a diaphragm, I always saw these in text books and old school sex ed classes, but I've never heard of anyone using one?
Help please! I want all opinions! (I'm in Australia and spermicides aren't available here).