Hello, during all my orgasms there is no ejaculation happening. my body tenses up and the orgasm occurs but no sperm is coming out of the penis until the orgasm is over. then it just slowly flows out. why is that?

This is more characteristic of older men whose sperm flow loses force through the years. You don't seem to have complete retrograde ejaculation where sperm is released backwards into the urinary bladder. Could you have partial retrograde ejaculation? Where you have normal orgasms & no erectile dysfunction, you still are very capable of enjoying sex. If you still have concerns, consult a urologist

If the muscle surrounding the ejaculatory duct goes into spasm this can happen and then when it relaxes the collected fluid gradually trickles out. There is no specific treatment for it. There is a possibility that it may improve /go away. If not pl see a Urologist for evaluation. Good luck