Firstly chill out, it's only hair and stressing will not make what you cut off reattach to your head. Refusing to eat or sleep and suffering anxiety is the fastest way to UNhealthy hair. Research your government's healthy eating and lifestyle guidelines and follow those, practice stress management techniques and get some early nights - models with a professional attitude eat nutrient dense food, keep themselves fit and get their beauty sleep.
Eight months without heat will be enough to grow perhaps four inches of virgin undamaged hair. It isn't enough to repair the damage already caused, that is impossible because hair is dead. Sometimes the ends are not salvageable and need to be cut off as you have rightly done, hair that is only somewhat damaged can be patch repaired (temporary) with ingredients like hydrolysed protein, coconut oil, ceramides and panthenol.
If you want longer healthy hair you can have that, but you can't have it instantly - people with longer healthy hair work hard over years and sacrifice things like heat styling. Models absolutely baby their hair away from work, most don't get to live like the rest of us and abuse their skin, hair and body: in many ways it's a 24/7 job. They are expected to rock up to castings with air dried hair and naked skin, so their natural beauty can be seen.
Heat styling even once every two weeks is damaging, especially if you use higher heat or your hair is not BONE dry. Maybe give your flat iron to someone for safe keeping and practice heat free methods like wet wrapping? Also next time have a curly specialist hair cut - see the salon reviews tab on the main NC site. Once you have a style that works with your curls you will have a unique look, long or short is not relevant you don't have to look like every other model but you do need to be healthy inside and out. That means mental health (stress/ anxiety) and physical health.