I visited a massage parlour recently and at end the massage provider ejaculated me by sitting on my penis and rubbing with her vagina and it was non insertive. Both of us had bath before and after. I am not sure if she stimulated me with her vagina or pelvic area. What are the chances that I contact STD or HIV. 

Welcome to our Forum.  Thanks for your questions.  The encounter you describe was low risk.  The technical term for your non-penetrative exposure is "frottage" and frottage is a form of masturbation.  Masturbation is considered no risk for most STIs including HIV.  No penetration (and if there had been penetration, you would know it), no risk for gonorrhea, chlamydia, HIV, etc.  Theoretically if she had syphilis or herpes sores on her vagina that might have been transmitted but this is quite unlikely.---

Thank you Doctor!