High testosterone and PCOS?

I've had high testosterone levels for the past four years, I've been underweight the whole time, so no weight gain. My doctor thought I might have PCOS so he had me do an ultrasound inwhich they did not find any cysts. My question is there any way I could still possible have PCOS even if my ultrasound came back normal? Also my doctor put me on Yasmin the birth control and my testosterone levels went back down to normal. I got off of it about a year ago and my testosterone levels are up again. Is it normal for some women just to have elevated levels of testosterone? I feel fine and I actually like the higher testosterone as opposed to normal levels. Sorry about all the questions my doctor does not do a good job of answering them.