my (very unexpected) first time [MF]

I, 19yo and virgin at the time, was at a festival with 8 friends last year. We arrived Wednesday although the bands started playing on friday. Thursday was our drinking day, and holy shit did we drank much. We already started at like 10 am. At some point, around 3 pm, our camping neighbours, 3 very pretty girls, came over and asked whether they can drink with us. I started to talk to one of the girls (24), Lisa, but I cant remember everything cause of the alcohol. She was a tiny woman, with an average body, but damn she had the biggest tits I have seen in person until now. I didnt do any “aggressive” move that could hint my interest toward her. She made every move and I just agreed cause why not. At some point she took my hand and played with my legs when we were sitting in a circle around a grill. Later she wanted to take a walk with me, I agreed and we walked a bit. suddenly she started kissing me and my boner grew as fast as it never did before. It was also my first kiss there btw. The sexual tension between us was already very noticable. When we came back my best friend looked at me with the “go for it bro” kind of face ;). But u know, I was a virgin and didn’t know what to do at all. I just went for the alcohol because it helped me to don’t stress out. Later in the evening, out of nowhere, she asked me, whether I want to sleep at her tent or she in mine. I struggled a bit, but agreed to the first and we went to her tent.