A 7" penis isn't freakishly large. That's around my size, I've gotten a lot of "this is the biggest thing I've ever seen", "it's bigger than my arm!" and all that, but it's really only 1-2" above average.
I've only been with very small girls. Eating more than I do on a regular basis they still fall into the "dangerously underweight" area for their height. It normally hurt them the first 3 or 4 times we had sex. Not to toot my own my own horn, but quickly thereafter I became their benchmark for the perfect member. If they told me to get it surgically altered I would have politely told them to go fuck themselves. Mines as big as it's going to get, yours is designed to deliver babies.
You should start by just having it exist inside of you. You should probably be on top so you can go at your own pace. If even this is just uncomfortably large, have him give you oral sex and use lubrication. Get used to it inside of you before jumping to the sex.
When you do finally have sex, take it slow, and don't take it all at once. If your boyfriend is any kind of a decent guy and wants to keep you without going under the knife, he'll work with you to make it a good experience.
Have you told him "it's too much, we need to do something different"? Or are you just letting him pound the snot out of you?
A 7" cock half way in is probably a lot less than what you're used to dealing with
On a final note, if it's unbearable painful at all stages, that can be a medical condition caused by mental or physical conditions. It's also definitely something wrong with your hardware, not his.