Thanks for your query.Based on the facts that you have posted it appears that you have problem of Premature Ejaculation
In absence of any major health issue the cause of premature ejaculation is mind related and due to performance anxiety.Following measure will help you to boost up your confidence and getting good erection.and delay ejaculation.
1) Practice regular exercise for 45 minutes followed by meditation
for 1/2 an hour in the morning.
2) Take high protein diet rich in vegetables and fruits and Vitamin A
3)Take anti oxidants like Almonds 5-6 everyday..
4) Avoid alcohol and smoking..
Consult qualified Urologist
for evaluation and further treatment.