Bogus Seat Belt Ticket?

This evening I decided to take a drive down Siesta Key, Florida- which is commonly known for it's beautiful beach, it's gorgeous sand and it's incredible amount of police officers, the random pull-overs, basically all harment related to the cops. I came into the village, had reduced my speed to 20 as instructed, watched for pedestrians, stopped properly according to signs. I came to a stop sign, noticing that a few people were pulled over to the side of the road. I turned my music down, trying to avoid unnecessary attention. Before I continue, I'd like to give a few details- like my dress is denim and matches my seat belt, my are big, forcing the seat belt further to the side of my chest rather than across the middle and my windows are tilted and were half-way up. I was pulled over, he asked if I knew why I was being pulled over, I told him that I did not. He told me that a deputy, not himself, saw me cross a stop sign while not wearing my seat belt. I was very honest with him and said, " sir, I've been wearing my seat belt the entire time" I explained that it may have been pulled over, but it was most definitely on. Another lovely detail, my car has a very LOUD and obnoxious beep to ensure that both pengers in the front seat are wearing their seat belts. It was not beeping, and my seat belt was on when he pulled me over. It's a 160 fine. I'm really unhappy with this, especially due to the fact that I am an easy target being an eighteen-year-old driving by herself. I want to contest this. My question really, would attempting to contest this be a waste of my time being as it's my word against his ( not even the deputy that pulled me over.)