I buy my groceries in small quantities too, so I end up going to the same grocery store a lot. The greeters definitely recognize me.
I have those thoughts that they are probably thinking, "geez, she eats a lot!" Or something like, "wow, she is buying cookies and no fruit? She should stop that and buy something healthier." I still go, but it's definitely awkward.
One night I went in there and one of the greeters said something like "Oh, you're right on time!" And I was like oh god, I really need to start changing up my routine a bit.
I also can relate to thinking that all the cashiers/other employees/people behind a counter are judging you. I used to work at a grocery store as well and I would see a lot of the same people come in. I never really thought anything of it, and I can assure that mostly everyone else doesn't really care either. They are more focused on getting their job done and going home. If anything, a friendly (regular) face is something to look forward to.