I can really only have orgasms when I'm on top also! Basically the reason for the is because when I'm on top I can control what his penis touches most of the time which helps alot out with him hitting my g spot! I basically trained my body to have orgasms in different positions! Like being on top an stopping myself right before an orgasm hits, if you do that a couple of times and rotate to another position, it usually helps you have an orgasm! PLUS, that is a "Tantric" technique! If you stop yourself from having the orgasm a few times it helps make your actual orgasm REALLY intense and wonderful!