I Feel Mocked

At both of my previous jobs my bosses all mocked me. The first job they even admitted they only hired me because they were desperate, and I was desperate so I stayed. They wouldn't hire me because I was apparently not smiling when I handed in my application. Throughout that entire employment, my boss continuously pointed out every little flaw in my actions though I was only doing what my trainer told me to. I was taught by the assistant manager and apparently taught wrong, and I took the fall for it. They did not trust me to handle fast paced work on my own and I had to forcefully prove that I could one night, which seemed to work. They delayed in teaching me the next steps until a few days before they fired me.
At the second one they had me working overtime so much so that my friends and family thought it might be illegal to do what they were doing. I was never instructed to use a timesheet, didn't know there was one, which lead to me losing some of my pay in the end. They would change my work schedule without notifying me and I would either be too late or too early or on the complete wrong day, though I made an effort to wake up at 3am just to call in and double check. They laughed in my face when I made mistakes and then berated me when I fixed it on my own, but they offered no solution or help. Eventually they fired me by slowly waining of how many days I worked until one day I physically came in to check the schedule and my name wasn't even on it anymore. I gave them until the next schedule change to see if they would even notify me that I was fired. When I called them they didn't answer and I received a text message from my assistant manager saying "Yes, you're fired." and that was it.... I waited nearly a month and they did not have any pay checks for me so I had to write a demand letter. After that I received it promptly with no explanation whatsoever.
Since then I've been finding it incredibly difficult to find a job. I'm not incredibly social, so it puts a limit to choices that would be flat out stupid for me to even try to apply for. After these experiences and more, I just never want to work in customer service type jobs ever again. I know exactly what I want to do, but I can't find any jobs to get me closer to my goals. I feel like my only choice for income is more meaningless time wasting ****** jobs that drive me insane and make me depressed. I don't know what to do, but I keep looking...