And second, a needle isn't going to be facing at 90 degrees for you to step on. And third, needle pricks rarely result in disease transmission because even the inside of needles can get too cold or too dry or too unsuitable in other ways for HIV or hepatitis to survive.
I think that you would know if you stepped on anything sharp. You are irrationalizing the woman and her reasons for sitting in her car. Maybe she was waiting for somebody? Maybe she was talking to someone on the phone via bluetooth. I myself do this and leave the car running while I'm talking. Instead of thinking the negative, try to think of the positive reasons she would be in the car.
Your foot is tingling beause you have become so wrapped up in the "what-if" that you are actually experiencing symptoms. The mind is very powerful in this way.
I use a needle at work every day to poke holes in foil tops. I reuse the needle because I'm not working with anything dangerous. I cannot tell you how many times I jabbed that needle into my finger because I was distracted while putting the cap back on. Trust me, you would know if you were ever stuck by a needle. It flippin hurts and bleeds.
So first there was no needle therefore there is no chance of you getting anything and this woman was not a threat to you in any way.
I'm sorry i completely forgot to add that my foot is now tingling.