I'm wondering if anyone can help me find an online service for preventive medicine? I've already tried my best, but nothing I've found has helped me solve my problem.

If you are looking for preventive healthcare services then you might want to check and compare https://ways2well.com/ . They focus on doctor visits, extensive lab testing and personalized wellness plans. It’s a handy reference if you’re looking for platforms that are focused on long-term health and not just treating symptoms.