Certainly you put yourself at the risk because unprotected anal/vaginal penetration is the sole route of HIV transmission.
Having said that, awareness of HIV is quite high in the cities like Bangkok and in particular among the CSW because of the frequency of their exposures. The test reports of the two girls should also give you some relief, though such tests are not 100% reliable because a single test without the information of previous exposures is not conclusive.
Administration of PEP is done under medical guidance from a qualifies doctor who is much more competent in assessing our true situation based risk. To answer your questions,
- Your risk is there but not very significant.
- Your worries are natural, but stay calm and relaxed because it is believed that your risk is not significant, secondly undue stress and anxiety does not reduce the risk, you were exposed to
- Starting and then stopping PEP, both on your own was not a right course of action. Anyway, since you have already stopped it, do not resume it, because it is ineffective after lapsing 72 hours.
- Not necessary, a PCR test after 10 days of exposure gives you a very good and highly reassuring indication, later to be confirmed by an Antibody test to be done a month after the exposure