Thanks for your query.Based on the facts that you have posted it appears that you have premature Ejaculation
and have been trying some sex techniques to delay ejaculation.
In majority of the cases premature ejaculation is 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
You can take medicines like Seldanafil and Dapoxine after discussing with your family Dr .This will help you in getting good erection and delay ejaculation.