Just live in the moment, don't stress about cumming. Just enjoy how the moment feels to you. If it isn't feeling right for you, try something different that you think might feel better or turn you on. You're young and have plenty of time to experience it all. You'll be fine. Try all ages for ML partners and get a feel for what suits you. Some have a better client relationship than others so don't go putting pressure on yourself. Mind you some ML's get treated like shit so if you treat the lady right she'll appreciate you more