A few people mentioned trichotillomania here and I hope I can share some advice I've seen as useful to a friend of mine. CBT (cognitive behavioral therapy) is often first recommended to those who have access to therapy. My friend tried this to limited success, but it can really help some people, so definitely give it a go if you haven't.
She started using 5 HTP which helped a bit. She moved to the use of Lithium with some success too, but was moved onto Clompiramine (an antidepressant) coupled with Naltrexone. This really helped her and she has been able to keep it under control since! I'd just recommend seeing what options there are out there to help through your GP and therapist.
The important thing to remember is that hair usually grows back, even when pulled out. It can take a while I'm afraid, sometimes quite a few months, but it does tend to grow back over time. If the follicle gets damaged then there's a chance hair might not grow back, but generally speaking it will come back. Trichotillomania sounds like a really hard thing to deal with - try and do your best to be proactive with the different treatments available, until you find one that helps!