There are subsections of this forum that are set aside for just Christians. I think this sort of question, given your framing of it, is better suited there. You could ask a moderator to move it for you (just use the report button to report yourself and ask), or you could just start a new thread there and let this one die.
But since you are here ...
- If it doesn't feel right, just don't.
- If there is alcohol abuse in your family, then don't.
That said, I think it is worth the time to figure out why you have guilty feelings. Is it because of a strict upbringing? Is it because others look down on you? Who are these people and what are they to you? (These questions aren't meant for you to answer here.)
The whole stumbling block thing I've never understood. When I was very young, my family went to a church that thought going to movies was wrong. "Disney
might be ok, but we wouldn't want to be a stumbling block." Really? If I go see Bambi, someone might conclude that Debbie Does Dallas is cool. This line of thinking never worked for me. People who would actually draw that conclusion shouldn't be allowed in public. (I exaggerate for effect.)
Drinking is a little different since someone people might have a problem understanding limits. But are these people adults? Have they had no instruction in life? They can't tell when they feel woozy that they might want to stop drinking? Even if they were susceptible, how exactly would there observation of you have 1 beer make them stumble?
If I am around an alcoholic, I don't drink. If I can tell or I've been told that someone gets uncomfortable around alcohol, I don't drink -- at least until I understand the situation better. But surely strangers aren't watching me and drawing conclusions about how to live life. I mean, I've never done that. Have you actually observed an idiot burning rubber and almost hitting a lamppost and concluded that you too should do this? I mean since you have a drink now and then, I hope I can conclude you are an adult. I don't think adults look at other random adults and suddenly conclude from ridiculous behavior that they should be ridiculous too.
Beyond a few courtesies I mentioned above, I wouldn't worry about being a stumbling block.