BL2 Enemies and Bosses are way below my level

I am level 50 and recently played some BL2 DLC in the Handsome Jack Collection. The Snowman boss, the Wattle Gobbler, and the Pumpkinhead boss were all level 43. I am in Tru Vault Hunter mode. Anything I can do to make sure future bosses and enemies are my same level? Thanks!

Yes, Either complete the main story and things will scale to 50 automatically, or go into UVHM. Since that involves complteing the story, it is pretty much a moot point.