The Guys at Work Just Don't Understand. :(

I work in a tire and oil express shop. Since the work we do is quick, we have a high turnover of vehicles in the shop. I also work mainly with men, with the exception of one female technician. My job is to greet customers, take their orders and get their vehicle information and communicate it to the techs. They often go shopping at the adjoining supermarket while waiting for their vehicles to be done.
My period is so heavy that I am afraid to sit down at all for fear of having an accident. My co-workers do not understand and I have, in the past, been subject to constant redicule. They get mad at me because they want me to drive the vehicles in to the shop after I get the VIN and other information that I need to get. When I try to explain to them, the guys get upset and weirded out and the lady tech rolls her eyes (obviously, her Aunt Flo is not as mean as mine). I am terrified of the thought of sitting in someone else's car and having an accident. How embarrasing would that be?
I have had accidents that have seeped through three heavy duty pads, underwear, a pair of bike shorts AND my work pants.
I have tried EVERY "so called" heavy duty pad on the market and using a tampons are worthless to me. In fact, there was only one maxi-pad that ever worked for me... and they got discontinued. (I have called the company a few times to complain).
Those of you that have been there, I feel for you. Not much we can do about it, but know that you're not alone.