Hi there, and welcome to the board.
You are not imagining things with the increased tolerance. It is bound to happen with regular use. It is the nature of the med, and if your pain requires you to take them on a regular basis, it would be unusual to NOT notice the tolerance issue.
Of course I am not a doctor, but I don't think it would be wrong to be honest and mention this to your doc. Don't tell her you want a stronger med, or more dosing, but just tell her exactly what you told us in this post...that it isn't working as good. Tell her the pain scale estimation of where you are now. Giving a doctor a pain diary is also a good idea, tracking a week of med usage and pain scale estimations every couple hours. If you want any help on building a pain diary, let me know and I'll give you more info.
I wouldn't ask your questions in front of a pain class, just because you never know who these other people might be, and your doctor might not want to tell you in front of them that she is willing to up your script, because they would expect the same and might not have your same situation. Definitely talk in private. (I'm fairly certain you probably planned to do this anyway.)
Don't be scared to ask for the relief you need. If she is not willing to help your pain, then consider seeing a doctor who will. We shouldn't have to be scared to ask for our needs to be met, and it is VERY understandable in this society why we have to be scared, with all the abuse going on. Put it in terms of telling her the problem, and letting her suggest the solution (which will hopefully be to tell you that you can take 2 tabs, or change to something long-acting). Never make the suggestion to take more, or to suggest a certain drug. They always flag this as someone drug-seeking....They never take this as you knowing yourself well, and doing your homework. Sad, I know.
Anyhow, if there is anything I can do to help, please feel free to ask!

Sara