need advice ..

so i am very sexually active and i have been for like 4 years now and i have had many different partners. but i still don't know when i finish...... or what its like to actually finish...... i've tried masturbating. i know i get to like an intense period during sex and then i just... get bored (idk how else to describe it) sometimes i think i have but other times i just don't know i just get bored and wait for him to finish. help/advice please???? what does an orgasm even feel like?