What Are The Chances Of Getting STD After Unprotected Sex?

Hi, I had an encounter 3 days ago with a girl i met. She is one of my good friends best friend and i was at a party when it happened. We were both drunk and we hooked up. We had unprotected sex for 5-10 seconds but stopped because she had her period. When we stopped i had blood on my penis. I washed it off and left. I talked to her the next day about it and she said it was her first time having unprotected sex. She also said she had been with 2 other guys but used protection both times and has had no symptoms of any std. I talked to my friend (her best friend) and she confirmed. She has no drug history. I'm wondering if you could give me any feedback on what my chances are of getting an STD from such short exposure (5-10 seconds). I'm freaking out and have lost some sleep over it. should i be worried?