I can understand your problem.
Here are a few things you should do to delay ejaculation so fast.
1. Indulge in a lot of foreplay before proceeding with intercourse.
2. Take intercourse slowly, don't go too fast.
3. Have a high protein diet, avoid smoking and drinking.
4. Do pelvic floor muscles strengthening exercises everyday.
5. Follow the start stop method while intercourse which means, when you feel you are about to ejaculate, just pause for a few seconds and then start over again.
Consult a physician in person for further examination and management.
Dr. Anil Kumar Jain.