They're probably not thinking about you.
If they are thinking about you, their thoughts about you are a drop in the ocean of the thoughts they have in the course of the day.
Moreover, the thoughts that they do have about you are constantly shifting like the beads in a kaleidoscope: the picture is in constant flux..
However, there's a further problem: what people think about you, in as far as they are thinking about you at all, is not discernible.
Even if they tell you, they're only telling you a fragment, and people are notoriously bad at expressing themselves accurately. Even if it's true in that moment, it can change in a flash.
If they don't tell you, you have no method of discerning it, as you're not a mind-reader. Let me repeat that, you're not a mind-reader. Even if you're 'very intuitive', a 'real people-person', 'emotionally intelligent', etc. Sure, but still not a mind-reader. You're not the Captain of Knowing Things. You're not Mystic Meg. You're not the Wizard of Oz. Understand? That make sense? Super!
On the rare occasions people do tell you what they think about you, and what they say is accurate (as a reflection of their thoughts), either it's untrue or it's true (as a reflection of reality).
If it's untrue, it's of no consequence.
If it's true, either it is important or it is not. If it's not, it's of no consequence.
If it's true and important, if it's old information, it's of no consequence.
If it's true and important and new information, either you can do something about it or you can't. If you can't, it's of no consequence.
If it's true and important and new information and you can do something about it, fix it, and thank them for telling you.
Any questions? No? Great. Now you can get back to what you were doing.