I'm a 'non-drinker' but last night I drank for the first time, and I feel guilty.?

It's the end of my freshman year of college, and I came into college planning to not drink; this is something I talked about with my friends and family before I left for college. Every time I've been around drinking this year, I've politely declined and said it's just not for me, but not in a judgmental way. People have come to know me as someone who doesn't drink, and lots of people commend me for it, especially adults who I really look up to. Most of my friends at home and school don't drink, and I'm sort of categorized into that 'nice, sweet, innocent' girl category, mostly in the admirable sense. It's sort of become part of my identity. And, I'm not going to lie, it was one of the challenges of getting used to college. I felt a bit isolated in my choice at times, but I didn't want to rely on drinking to meet people and I wanted to maintain the integrity of my choice, you know? But last night I was with a small group of friends who I've started to get to know and really like. They don't drink often, they're not the type to get wasted every weekend when they want to have fun. They're real, down-to-earth girls who I've really enjoyed getting to know. Anyway I drank a small amount with them, maybe 4 shots total, and had a great time. And I don't exactly regret it, it's just that I feel like I can't talk about with my friends and siblings because it might hurt them or make them wonder if I'm going to change. I don't plan to start drinking all the time now, I still don't want to do the crazy college house party scene. But I just don't know how I'm supposed to feel about this...I'm on a sports team here at college and if people found out I'm sure some would say 'good for you' but some might think less of me or see me as less innocent and treat me differently maybe? And I don't want to disappoint my home friends (the ones who don't drink) by telling them. I trust them with my deepest secrets, but this is different. And what about my non-drinker college friends who I've bonded with over the fact that we don't drink? I feel like they would judge me if I told them...anyway, does anyone have any advice or thoughts on this? Thank you!