Hi K..
Sucking is a learning process for many babies, especially the ones who have been traumatized at birth with an aggressive use of the sucking bulb (you know, the one that the doctor uses to suck out the fluid in the newborn throat as soon as the baby comes out).
Your baby is already 7 weeks, therefore you don't have anymore time to lose: call a lactation consultant or go visit her at the local hospital. If where you live you don't have this service, write me, I'll give you the number of the one that I use.
Lactation consultants are key for forming good nursing habits for both Mom and Baby and they can help you with the bottle too.There's nothing more important than your baby's health, these are his first steps to a good nutrition.
My baby learned to suck effectively after a week of biting my nipples. It took patience and a couple of exercises, but everything fell into places and I nursed (and still nurse) with no problems. He can switch my nipple and the bottle as needed and he never hurt my breast because he never developed a wrong sucking habit.
Call the professionals, they'll help you.
Good luck
S.