Breast pump!

Having issues pumping! It's hard for me to comfortably pump for 20 min my hand gets tired. I want to get that special bra for pumping but I'm a big girl and I feel like not only will the bra not fit right but I don't think it will hold the pump tight enough to my nipple. I have to put a good ammount of pressure just to get the pump to suck right. It's an electric Medela pump. Ugh. Any advice or am I just screwed lol