I have urinated 3 times since my last ejaculation. is all the sperm in my urethra removed?

There is no way for you to know. Having repeated sex without condoms and contraception has the same risk for unintended pregnancies and even STDs. Sperm can live up to 5 days. I perform vasectomies on men, and I tell them to do a semen analysis 6 weeks later and after 20 ejaculations. Only then do I tell the overwhelming majority that they are sterile.

Yes. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV, Flu and Covid vaccines. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines