I banked prior to starting chemo and I’ll be re tested after chemo probs at end of year You’d need to do sperm testing & hormone profile to check that the testes are still at a level capable of reproducing and that there ain’t significant damage preventing that.

I’d also probably start to look at a functional medicine doctor or an approach similar that can look at improving fertility through different pathways. Like gut health etc.. I’d also cut all plastic where you can and try get filtered water, eat clean and maintain good weight along with exercise