Weight Loss Journey

Hello Everyone! Well I've started my weight loss journey at the beginning of this year. I had already planned my workouts for the month of January but I didn't go through with it because I was really stressed about not getting my period. Well, turns out that I have hypothyroidism and everything now makes sense as to why I'm always sleepy/tired, low energy, easily cold,ect.
***To make this short
Gender:Female.  Age:20
Current Weight:150 lbs . 
Goal Weight:120lbs.  Height:4'11
***My Plan is to lose 30lbs 5 Months
I know some people have lost that much weight in 3 months but I don't want my health to worsen.
I'm using FitOn a new workout app that I really like so far and I'm working out 3 times a week. I'm already planning my meals and I'm doing 5:2 fast where I fast for 2 days of the week but I'm allowed to eat 500 calories and tbh I know I can do it but I'm unsure how it'll affect me.
Is there anyone who has the same health condition as I do and still lost weight?
Will fasting affect my health in a bad way?
What are things that have helped you lose weight with or without any health conditions?
I'm new to this forum and all I want is to share my journey with you all in hopes to motivate ya'll and encourage ya'll to do it. I plan to weekly update to keep myself accountable.