Try increasing your supply by eating oatmeal and drinking Mother's Milk Tea.
Nursing your baby will increase your supply naturally- the more you actually nurse, the more supply you will have.
I, too, have rather large breasts and did get more with manual Avent Isis, but also used the Pump-in-style with car adapter. I listened to low relaxing music, smelled an article of my baby's clothes (or blankey) and looked at a photo of her or closed my eyes while pumping.
While you are pumping at home you can try nursing on one side and pumping on the other.
You might try calling a lactation consultant, your hospital about renting a pump from them, contacting Medela (like some of the others have already metioned!) and joining La Leche League (yes, some of the moms pump A LOT and have lots of knowledge!!)
It CAN be done! I worked 60+ hours/week and breastfed my baby til she was 3.5 yrs and pumped til she was about 16 months.
Hope this helps!