¿¿ SCARY ?? Weight Loss

So I'm not too TOO worried about it, but I don't know how to feel about my weigh loss. I'm currently living w my SO's, his mother (her bf stays over occasionally) and his 2 sister's (21 & 23) in this 3 bed apartment, his sisters don't really do anything to help out around the place and are home all the time. I work part time at a retail store, my SO does security full time, his mother is a manager and his sisters don't work. In the beginning my SO's mother would buy food for the apartmnt, and some good weeks when I could afford it I'd buy food for myself. Now to sum everything up, I went from 189 to 149 [5 '4] in 4/months. There's weeks when i do eat 3 times a day and others when i don't. And now i feel like most days i only eat once a day because there's never anything to eat and other days I'm eatting fast food. I try to drink LOTS OF WATER but Im worried about my health, i don't have insurance so I don't know who to talk to about this professionally. As i continue to loose weight my SO thinks I shouldn't worry about it, and i thought it was nothing but i feel like i'm loosing muscle mass (specifically in my legs), and I'm afraid of my metabolism because my family has a history of thyroid and blood problems. I've been telling myself 'you're just FASTING.. monks don't eat.. you're not gonna die' but I find myself forgetting things and not being able to find the right words to say when i talk.

I mean i'm happy im smaller but, i want to be healthy too and i LOVE FOOD but i feel hungry ALL THE TIME.

SHOULD I BE CONCERNED?

P/S me and my SO WILL BE moving out in January 11 2019.