Fastest way to lose weight ????

firstly let me start by saying you look great for your age. i wouldnt have thought 113.
As far as the weight loss. i suggest tracking your calorie intake via My fitness pal. there are alot of secret calories that alot of people dont realise they are taking in until they enter all there food into the program.
Find you ideal Calorie intake to lose weight depending on age height etc.
If your not injured then exercise and weights..

Thats a very broad answer. The answer can only be refined with how often you can train, what your eating now, medication etc etc. But the basic answer is if you take in less calories than your body uses , and exercise as well, you will lose weight.
PM me if you want to go through it all in depth

Unless you're under 5', there's no need for you to be 100lbs.

A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition