Would weighing roughly 150 lbs at 6'3 be considered unhealthy?

Your bmi is probably in the underweight category. That doesn't mean one is automatically unhealthy, just like being in the normal range doesn't make one healthy.

Yes dear, you need to put some weight on

It’s okay I’m tall and skinny too some people can’t do anything about it

It depends on the width of your skeletal structure.

It's slim

That's pretty anemic