I think that was a good choice! Might as well try an IUI, which will still up your chances as opposed to just timed intercourse, and then save the money for another IVF try down the road...if you need to (hopefully you don't ;-)
How big is your mature follicle? The smaller ones might very well catch up by the time you have your IUI. They usually grow about 1 mm a day early in the cycle and 2 mm as you get closer to O, and since you already have a mature follicle, I would think the smaller ones are now growing at the 2 mm rate.
:-)
I am so very sorry... I hope that smaller follicles will catch up by the time of the IUI.