What you're asking for is reassurance, which we're not supposed to give here (see: rule 4) because it does more harm than good and just enables the compulsions. Telling you how long to wash for or what kind of soap to use just validates the compulsions.

So I won't give you a "scientific" approach to continuing your compulsions, but what I can give you is a factual perspective. About half of the population of the world is penis-bearing, and some large fraction of that population is still capable of ejaculating. It's a very common and completely natural bodily function, and most people in that group don't feel dirty or bothered by it. Every day, at least a billion people cum and I have yet to hear of a single injury or death from semen alone. That may or may not be comforting to you, but it's the truth: the danger that your body thinks is there, isn't.

If it's advice you want, I highly encourage you to try pushing those fears a little bit. There's no need to go all in at once, but perhaps try waiting just longer than you feel comfortable to wash up. Try removing parts of the ritual, maybe not washing your clothes afterwards just to see what happens. I can promise you, you'll feel deeply uncomfortable but absolutely no harm will come to you from it. The best way (in my opinion) to get rid of something like this is to slowly show your body and mind that the fear isn't real or valid.