Definitely No!
There's nothing wrong with you!
Just because you aren't crying or feeling very sad about her doesn't mean you don't love her, and that she doesn't love you!
Some people just express their emotions differently, and you just miss her and feel kind of sad deep inside, while your mom expresses her emotions outside by crying.
This is a very common thing to happen, I know I've felt the same way you have too, but if you can ask yourself if you loved her and you can answer yes, then you shouldn't feel bad at all.