Is it normal that i have trouble identifying my emotions?

Sometimes when people ask me how I'm feeling I honestly can't tell, I try to tell them that I don't know but they always look at me weird when I do. I don't think I feel nothing, I must be feeling something and I just can't tell. I don't know how to find out how I feel. I've tried to think about it, concentrate really hard on it, find the words to explain but it's like they're just out of my grasp. I'm just not capable of it, I don't have the ability and I don't know why.