Welcome to HCM,
Size ans shape of penis is always determined by your genes.
There is no specific medicines medicines to increase the size.Don't worry ,take good healthy diet rich in protein.
To prevent premature ejaculation
you have to spend some more time in foreplay.Avoid stress
and don't get hyperconscious during sex.Concentrate your mind in natural way of sex ....Some medicines are there to prolong the sex time.
Consult your physician for it.