Clen isn't a miracle drug. In my opinion it's really not that great. It will help though. 14lbs in that time frame is going to be hard, at least if done right. Sadly, you won't be able to know how it will affect you until you try it. It affects some in better ways than others. If you want to try it here are the basics:
You need to drink at least a gallon, preferably more, of water a day.
Take 3-5 grams of taurine since clen strips this from you
Take potassium
For usage start out by taking 20mcg a day. Take it all at once preferably in the morning. If you do cardio in the morning take it after the cardio. Up the dosage every day or two until you can't take the side effects. I wouldn't go too much higher over 140mcg for a woman. Run at your max until two weeks total time is up. Then you're off clen for two weeks, and then you begin another two week cycle except this time you have a good idea of how much your body can handle. In the off two weeks you can take a ECA stack or some other thermo.
Sides can/will include: cramps, sometimes in bad places, twitching, shakes, headaches, racing heart, and sweating.
If you are not feeling anything off of the clen at a high dosage than your CNS is off which may be due to a lot of stress, coffee, etc. Which if that is the case then clen might not be the most effective thing for you.
Diet and excercise are the best things and clen won't work at all if those areas aren't in check. I know you said yours are, but people think this is a miracle drug and get sloppy and then when they don't see results wonder why.
Good luck.