STD through indirect contact with prostitute?

[50144]

I received an unprotected handjob from a prostitute a few days ago. I know that pure handjob doesn't have any risk. However, some behavior from the prostitute makes me fear about STD from this incident. I was naked and she was wearing t-shirts (Without bra) and pantie. She wanted to give me a blowjob but I rejected and asked for a handjob (without condom). She then flipped over her pantie to show me her genital then use the same hand to touch my penis (Last for a few seconds). She also use her breast to touch the head of my penis (Last for a few minutes). After that, I was touching her genital with my hand (No fingering, just touching). I also used the same hand which touched her genital touching her breast. I didn't touch my genital with that hand and I end up ejecting between her thigh and genital. My genital didn't come in contact with her genital or body while ejecting, I was ejecting above her thigh and genital. I noticed that she didn't shower or wash her body afterwards, she just wipe off my sperm with paper towel then wear her clothes. I was scared because what if the previous guy did the same things like me? I have a few concern about this incident, assuming the prostitute have some sort of STD:

1) When she flip over her pantie, her hand must have touched the inside part of her pantie (where her genital located), possible that she have touched her genital as well. She also used the same hand touched my penis, although this action takes less than a few seconds, is it possible that her genital fluid / STD transferred to my genital via her hand during this action?

2) As I mentioned, she seems not to take shower or wash after each service, when her breast touch the head of my penis, is it possible that there are genital fluid / STD (Either from previous guy or the prostitute herself) left over on her breast and transfer the STD to my penis? (I must add that at the time of this action, her breast looks & feels dry)

3) What is the overall risk of this incident? I read lots of post that it is zero risk for HIV, am I correct? What about the others (Herpes, Syphilis, HPV, Chlamydia, Gonorrhea etc.)? Does the prostitute didn't shower or wash her body after each service has any effect on the overall risk?