You’re balding, probably AGA, check with your doc
Dude you are DEFINITELY thinning at the crown and I suspect slightly in the front too. First go check for a vitamin deficiency via a blood test (though I don’t think it is the cause, to be sure) and if everything is alright then it probably is androgenetic alopecia (aka MPB, you will go bald with continous thinning thanks to DHT buildup if left unchecked.).
Ask your doctor about finasteride (or dutasteride, a more potent DHT inhibitor) and minoxidil. Ideally topical for minoxidil and oral for fin.