Girl, make that appointment for May 19!! I had just done IUI #3 with my OB last November, and I had my first RE appointment at 12dpiui. I thought that my OB was a jerk, and though I was hopeful that the IUI would work, I was like you and wanted to get things going if I got another BFN. It took 2 months to do all of the tests and have a lap like my RE wanted before we could start trying with a new plan. I'm glad that I didn't wait any longer to make that appointment.
You know when it is time to move on, and it sounds like you are ready. Go for it, and definitely keep us posted