Is there anything you can think of that condoms dont protect against?
Anything transmitted skin to skin like herpes, genital warts and molloscum contagiousum off the top of my head. The most common thing you'll catch is a cold, although the longer you work the more resistance you build up (in my experience, at least).
What are your specific concerns? Nobody here wants to minimise a completely sensible and responsible desire to protect yourself, but in-person sex work means regular intimate contact with other people whose health status you don't know and it's still relatively rare to catch anything, even among people who do offer OWO. Unless you have a vulnerable partner (or one who doesn't know about your plans), this level of worrying is just not proportionate.