mad at HRM chest strap/readings for tubo fire

unknownndoll

so i am getting really mad about my HRM I just bought. I think it moves while i work out and dosnt get all the beats or something. the 1st time seamed fairly accurate. I am 140 lbs, 30 yrs old doing turbo fire.... so fire 55 said i was at 435 cal burned. then today fire 45 said i was only at 282 (I thought, gosh that is a bit low) and then HIIT 30 at 277 calories burned. I see others way higher than this. I looked down after one of the fire drill thing on HIIT 30 and my HR was like only 120!! then i adjusted the strap and it started to go up AFTER THE DRILL!!!

I hesitated to even by a HRM because i read they were not really accurate since it dosnt get your vo2 max (something like that) and that its just another estimate. Now i feel more frustrated than just adding in the minutes in my log. I dont NEED it to be 100% accurate since i dont eat exercise calories, but i wanted a better way to get a somewhat accurate calculation, especially after spending that kind of money on it. I dont know if i am wearing it too tight, too loose, if it slips from the right area, etc. I want it to just work. I dont want to stop my workouts just to look down at the watch to see if its correct and adjust the strap ever minute!!