Years ago, my boyfriend asked a similar question to my therapist - except it was about masturbation. She replied that if it's getting in the way of your normal life, that's when it's too much. If you'd rather masturbate than going out with friends, or living your life fully in general, that's when it's too much. I'm not sure if that's similar enough to help, but it seems like practical advice. If these thoughts are interfering with your friendships (putting your friends off, or insulting them, etc) or even if they are just upsetting you, it may be time to seek guidance. But I've never been in a guys head, lol so this all might be perfectly normal!
Wishing you well