I lost almost 60 pounds before anyone said anything. I complained about it here a month or so ago. Once, before anyone said anything, I went to lunch with my group from work. Everyone was ooh-ing and aah-ing over this guy who had lost 55 pounds. I had also lost 55 pounds but no one said a thing. I was like, what am I, chopped liver?
This bugged me like crazy and so I thought a lot about why it might be. One possible reason is that I carry my weight differently - that guy just kind of deflated, he carried most of his weight around his middle and the difference really showed. I have a very curvy figure and my weight is distributed all over. Very few people believe me when I tell them what I weigh - there's something deceptive about how I carry it on my body. That's a good thing, but it also means people don't notice the losses as much.
Another reason people might not notice is, if you're still wearing your old baggy clothes, your new shape just might not be showing that much. I have this problem, most of my clothes are too big and I don't look like much in them.
Another possibility, of course, is that they are noticing, but just don't feel comfortable saying so. Some women are so sensitive about their weight - I have seen posts here where even a compliment can send someone into an emo spiral of "she said I look good 'now' so she mean must I was a hideous fat cow before
*sob*". I don't have this issue; I know I'm fat and I know I look better now than I did 60 pounds ago - it's not an insult to tell me that! But still - with regard to someone else - I'd rather say nothing than risk unintentionally setting off some emotional trigger I don't even know is there. That is magnified in the workplace, where people are often (appropriately) cautious about raising personal subjects.
So just because no one has ranted and raved over your amazing weight loss, don't conclude people aren't noticing.