Any girl who is ok with raw f**king some random who picked her up at a bar has probably done that before, more than once.
People don’t walk around carrying their STD test results (which are only as valid as the day it was done). So even if she had the test results and could show you, it means nothing if she f**ked guys after the test. And no, getting a test after the unprotected sex doesn’t protect you or prevent anything. For HIV if can take months to show up, because the HIV test looks for anti-bodies. It takes time for your body to detect HIV and develop anti-bodies. But HIV would actually be the least of your worries. Herpes is much easier to catch and there is also no cure for that.
If you are ok with sleeping with a girl who is ok with sleeping with random men without a condom, then you are ok with getting herpes.
If you prefer not to get herpes, or any other STD but have an issue with sexual performance and condoms, maybe see if there are different brands you can use or train your d**k to get used to wearing one.
Or, get the girl to use a female condom.
Just remember that casual sex with multiple girls doesn’t mean it’s only you having sex with those girls. There is no monogamy in causal sex (that’s the point), and those girls are likely having casual sex with other guys also without a condom so the chances are high of getting an STD.