Good job losing the weight but yikes hes right you do have alot of loose skin, I’d question the merits of your diet and would suppose you lost your weight a bit too quickly.
The danger of cutting calories too much for too long is that it cranks down your metabolism and can catabolize your muscle tissue too, effectively digging you into a hole. Which can leave you looking both skinny and soft.
You definately want to ‘bulk’ but it will be a fine line to walk because if you did indeed damp your metabolism, too much excess can go to adipose quick. Eat clean, dont let your weight go up too fast and focus on getting your anaerobic work volume up. The greater your calorie flux, the greater your metabolism.