2 year old tank, minimal water changes, but nitrates are always 0

I am 100% sure my tank has been cycled and matured for a long time. Everyone is happy and healthy.

But throughout my entire 2 years of testing with brand new API liquid kit from Chewy, I always measure 0,0,0. I had one ammonia spike a few months ago due to plant die off/losing 3 fish, but everything is back in balance. I think I can remember 1 time where the nitrate test had a tiny tinge of orange.

I have 8-10 Pygmy corydoras, 4 Cory habrosus, colony of Neo shrimp, and many many snails. I also have a lot of plants. I do minimal water changes and don’t really have a fertilizing schedule, just a few drops of seachem flourish comprehensive like once every few months if I remember.

I got over all the algae problems maybe a year ago, but I am noticing a little staghorn algae on the tips of some Java ferns.

My question is how can I boost the nitrates to help my plants grow faster? Everything is actually growing pretty great but I’d like to see if they can be even better by trying to keep nitrates around 20ppm (or something like that?). I find it a bit weird that I never have any nitrates, but I think it’s totally plausible that the plants just suck everything up