How can you tell by your face?

Nicole
So I had no idea you could tell someone is pregnant by their face. My boyfriend said "My mom said you look pregnant." Well, my stomach is the same, so it's not that. I stopped birth control pills about 3 weeks ago, and I have some acne now and wear half the makeup I use to becuase of that. 
We use condoms 75% of the time and when we don't, he does not finish in me.
My question is, in what ways can someone tell you're pregnant or think you are, by your face? What do they look for, etc? 
I really want to know, and appreciate any replies. Thank you. Stories are welcome as well