Interesting that you find it "painful" to swish for even 7 minutes. Is that because you put oil of oregano in there? That stuff will burn if you have open sores. Is that what you mean? I zone out swishing while I go to the mail box, do laundry, answer emails, etc. I use sunfower oil. I reserve the coconut oil for eating, cooking and my skin.
As far as the health benefits, more benefits can be seen, I've heard, if you oil pull 2 or 3 times a day. So far I just do the morning before breakfast pull, but I may try it before dinner also. I usually do 10 minutes, but because I swish while multitasking, sometimes I've done it for 30!
Good luck with your oil pulling. I hope you get used to it and have no pain!