Hi Liam245 , you maybe having a bit of anxiety when you with your partner i bet , you probably nervous as well , thinking you got to do it right and stay erect , please calm down take your time , there is no rush what so ever , you got to relax , Viagra you don't need at all your age its all trial & error , please don't rush into anything , and if you are having intercourse Please use a Condom at all times ,take care & Enjoy your Teens ,