So my family, theyll freak out, me i want to lose weight...?

I currently weigh 122 ): and im only 5'3. I want to lose 20lbs within two and a half months to three months. I have the self discipline i just dont want my parents and family and even friends to freak out. They would freak out (most likely) because my doctor said i shouldnt go below 115 haha, which i think is bull crap...Help?