This may help
You can try the following method called the Squeeze technique which is used for premature ejaculation, and this may not help you. But, you can always try to find out whether it works.
Although 6-minutes can be considered adequate, you may want to increase the time, and that is understandable. You have to be patient and not rush into everything, as anxiety and emotional rush can reduce the time. Take your time and do not rush if you want to increase the time. I see that you are 45 years old and a doctor, so you may understand the next thing that I have written. With age, like women, hormone levels in men also goes down (called andropause) and it is normal to have reduced capabilities when you cross your 40.
When the husband feels that he is going to ejaculate, the wife immediately stops stimulating him and applies firm but gentle pressure around the penis where the glans (head) meets the shaft. She applies this pressure for 10-20 seconds. She then lets go, and they wait without doing anything for about 30 seconds. The procedure is repeated several times before ejaculation is allowed to occur