Does my stepmom not wanting me to see my dad ?

Ok so I'm 13 and I havent seen my dad like 9 months ago and it's like wtf! And yes my parents are divorced I live with my mom and my dad is suppose to pick me up once a month and stuff but everytime he says he's going to pick me up my step mom calls saying "oh I'm sorry honey your dad has to work late" but I hear my dad talking in the back ground I have asked my dad multiple times and he says no honey she will never do such a thing and blah blah blah but she's a ***** and she's always making my dad do things for her like cook pick up groceries take her here and there and pick up my brothers from school and more and it's like annoying