I can only have 1 orgasm.

It is not a problem.

After an orgasm, almost all men, and some women need to recover. This is called the refractory period.

How many times can you orgasm when you masturbate? How long does it take you to recover?

You need to make sure you are well lubricated, and stay well lubricated. Hard rubbing can also cause this swelling.

Change the way you have sex. If you recover from this fairly quickly, get your orgasm first, and again right at the end again after you recovered.

Use much gentler touch and plenty of lube, and see if that leaves you in a better state after your orgasm.

Make sure you are not sucked too hard, or that her pubic hair is not scratching you. Avoid bruising from grinding.

Get your orgasm right at the end.

Stop before you orgasm and move stimulation somewhere else until you come down a bit. Restart stimulation. Repeat this cycle over and over and you will end with a massive orgasm. You can also try this when you masturbate.

Make sure you do not have an infection or STD.

Best of luck!