Need more Calories!!

I (22F) have been underweight my whole life, same as my mom. It’s always been chalked up to me as “high metabolism”, and something out of my control that will never change.

I’m 5’7 and ≈100lbs currently. Highest i’ve ever been is 115, and that was while on birth control, years ago. I loved how I looked on it but I don’t want to have to resort to it again to fill myself out, because when I eventually go off of it, the crash is awful.

I have to admit I’m lazy and a gamer, so I’m not horribly active. Maybe this sounds stupid but I’ve always thought that sitting around and eating unhealthily/a lot is associated with gaining weight. Obviously not working.

Whether it’s throwing back fast food until I feel disgusting, or eating balanced home meals, nothing changes. I don’t have a great appetite. I’ve been calorie tracking over the past 6 weeks, and I found that my problem is I tend to eat on average 1500 cals a day, and only 3 DAYS did I hit the 2.2k+ cals that is recommended to me. I’ve been drinking shakes (boost?) but it’s recommended only one a day and they’re only 160 calories.

It is such a drag trying to hit 2k+ calories daily. I am simply just not hungry or have no appetite most of the day. I would appreciate pointers or advice.