I take my measurements pretty frequently (I'm a seamstress), and no matter what I weigh or what size I am, my right thigh is ALWAYS a full inch bigger than my left. (I don't drive that much, so I'm sure it's not toned muscle. LOL) I would assume that it's some combination of muscle and fat... I think most people are familiar with the phenomenon of their dominant side hands/arms/fingers being slightly larger, and certainly it's not at all uncommon for women to have differently-sized breasts (which are largely fat tissue). Likewise, people often have different-sized feet--which are mostly NOT fat. As a species, we exhibit
bilateral symmetry... but that doesn't always mean each side is a perfect reflection of the other.
...Which is to say, yes, it is hard to buy pants, thank you for asking.
But I don't think you're weird.