That puts your bmi at just under 18. Between 18 and 25 is considered healthy. I usually sit around 19 myself. I wouldn't listen to redditors, most of them think anything less than obese is too skinny. You've definitely got some wiggle room to gain a little if you wanted to, but please don't lose any more. As long as you're healthy and happy where you are, is what really matters I guess.