Is there a source that to serve Avoda zara it has to be served by at least a few people?
If I thought I served avodah zara would that now make it something served, and if I now bend down in front of it, it would be avodah zara? (I have terrible OCD about this because a different rav said it actually was avodah zara. but every other rav I asked contradicts him
I am not aware of any such idea, that avoda zara is only if there are three people who serve it. However, bending down in front of something does not make the object an avoda zara, not the bending being oiver on avoda zara! Did you actually think that the item you happened to bend down in front of has some special heavenly powers, or that you are subjecting yourself to it? If you didn’t think such thoughts it isn’t avoda zara! Whenever someone bends down to get something, are they committing avoda zara? Obviously not. Therefore, you have nothing to worry about.