6'3" and 137lbs - is this actually unhealthy? Starting aggressive bulk

So I'm 21, about 6'3" and weigh around 137lbs. I know that sounds crazy light but hear me out I'm not like weak or anything. I can bench 185-200lbs. But lately I've been thinking maybe I actually am way too light for my height?

My BMI puts me at 17.1 which is technically underweight but I don't really know if I should trust BMI or not. Like I feel fine most days and I've got visible abs and decent muscle definition. But 137lbs at my height just sounds wrong when I say it out loud you know?

Anyway I've decided fu*k it, I'm gonna bulk. Started 5 days ago and I'm going hard eating like 4000-4200 calories a day which is apparently a 1000+ calorie surplus over what I need. My goal is to hit around 155lbs in the next 10 weeks.

Is gaining 15-20lbs in 10 weeks realistic or am I setting myself up to fail?

Anyone have good tricks for getting calories in without feeling like absolute shit? The shakes help but I need more ideas.

Appreciate any advice. This is day 2 and I'm already feeling like this is gonna be way harder than I thought lol.