Don't feel too bad! - my friend, who is obese, has lost 32 pounds. I hadn't seen her in about 6 or so months. I THOUGHT it looked like she'd lost SOME weight, but I was afraid to mention it, for fear that maybe she hadn't, or maybe she didn't want to talk about it, etc. So I said nothing.
Later on, she mentioned it, and said "Can't you tell?" .... well, of course, I was semi-mortified! - because I'm all about supporting my friends in their endeavors! - so I explained to her that YES I could tell, and I wasn't "just saying that" to make her feel better, and congratulated her & wished her good luck in this long & hard road.
So take heart... maybe lots of people CAN TELL that you've lost weight, & they may just be a little shy to say so.