It's really good that you've found an online group, see what face to face groups you can get into as well. Also, don't be scared about telling the people you know - friends, family etc - that staying sober is your journey now. Anyone who is decent and respectful will want to help support you. Try not to look for any excuses as to why you can have "just the one drink". From now on, just keep it to being teetotal. NB I know it isn't as easy as just that (I've seen how hard people work to maintain sobriety), but don't even look at having "just the one" as being ok.
I said in a previous post that I'm pretty much teetotal. I'm lucky that I've never had a problem with drinking per se. My problem (which I don't really view as a problem) is that I have a deficiency of the enzyme that breaks down alcohol (ergo quite a hefty intolerance to alcohol). I can manage maybe 1-2 units before it hits me. I might take a very small half glass of wine with a meal (definitely no more than 1unit), but I rarely do this (I can count on one hand the number of times I have had a drink in the past year). When going out with people who don't know me, this sometimes posed a problem (in the past) as they would expect me to join in with drinking (particularly if I wasn't driving), I'd have to stand my ground and refuse alcoholic drinks (so I understand the pressure from outside places). Sometimes people would try and put pressure on me to have a drink, or they wouldn't believe me when I said that it would make me ill. Luckily, my friends understand and will never try and foist drinks on me - they also understand the history I have with XH (who was an alcoholic) so they're brilliant about how they are around me.
I think also that these days society is more tolerant towards those who do like to stay sober on a night out. There are certainly more non alcoholic drinks available. A couple of decades back, I was seen a bit like a social pariah for sticking to soft drinks. There'd be "happy hour", lots of places would give out free drinks, I'd see a lot of drinking games etc (maybe this sort of stuff still exists, I don't know). There was a big expectation that people would drink (a lot of) alcohol on a night out. Not great at all. It got easier once I passed my driving test (they'd accept me not drinking as I was driving). I think now, the expectation and assumption that people drink/should drink is a lot less. So, I think all the more reason to speak up and say that you want to knock it on the head and stay sober (and that you need their support). I think speaking up about it is part of having the accountability - in the same way that my friend and I will egg each other on about getting housework done and dusted, or batch cooking done, or our exercise regime for the day all done!
It's really no bad thing being sober at events though: you're keeping healthy, you're in better control of situations etc. I love it: no hangover, no worry about how I'll get home (I just drive), I save a fortune, no being ill, I get a good sleep and wake refreshed in the morning....with clear memories of a good night/event. :)