please help, my dog won’t stop peeing on my bed

i have a german shepherd/labrador of 4 years old. she was adopted almost 4 years ago, and she is my baby. however, she has extreme anxiety. she is afraid of loud noises, won’t go in certain areas of our house cause of fear, and will pee on my bed almost every night.

i’ve noticed the pattern of 3 things when she pees; 1. she pees for what seems to be the hell of it, 2. i take her out to pee before bed, but she just stands there looking dumb, and wont move off the porch, and 3. i forget to take her out before bed (usually after midnight), even tho the back door is open the entire day and into the early night to a large backyard where our other dogs (and her) all go pee.

this all started back when i moved out of my parents house into an apartment where she didn't have our other dogs with her, and i guess she was just more scared. she would literally shake when kids would be playing and laughing outside despite all my comforts, and started peeing on my bed there. she would pee on the floor inside when she was a puppy, but we trained her out of that (or so we thought lol).

i really don't know what to do, its always been a lingering problem, but recently its been practically every week that i have had to strip my bed apart and put it in the washer in the middle of the night. she will also pee on my parents bed, so its not just my bed. does she just hold it in from laziness?? she will literally lay in her own pee until i notice it.

someone please help me. my sister took her to the vet a bit ago, and they recommended some sort of medication but it didn't seem to help, nor has a trainer helped. what should i do? take her to the vet again? or try some at-home remedies? i'll do anything. i'm leaving for college again soon and i really don't want to leave this burden on my parents.