Try Clen from
http://www.universalkits.com/researchchems.htm -- if that doesnt give you the shakes then I don't know what else to tell you, maybe your body just doesnt respond to clen.
As far as another fat burner, Thermorexin from the AF Store has been getting some good feedback. T3 is something to investigate but definitely get some more opinions from other females who have used it because there is a lot of feedback on it, both good and bad.
Aside from that, diet will be key to the fatloss. Once you've nailed down the "eating completely clean" all that remains is manipulation of calories through adjustment of the macro-nutrients as well as looking at increasing cardio.
As far as missing your period, my understanding is that it is due to hormonal imbalance causes by the steroids but thats a pretty generic answer. I should probably let one of the females explain it to you a little more in depth.