Thank you for sharing your story. It sounds like you have faced so many difficult situations and have stuck through it. You sound very brave and I commend you for reaching out. Migration is hard, finding jobs and starting from scratch is hard. But you've also had a hard time in Syria and with your family. In light of all these difficulties and the fact that you are feeling lost and scared, I recommend that you speak with a mental health professional like a counsellor or a psychologist. These professionals can help walk beside you in this tough time as you settle down and can help strengthen you mentally so you are better equipped to deal with anything that comes your way. Is there a community health centre where you live? They usually have psychologists for free. You can also talk to your doctor about this.
Other self-care tips like meditation, regular exercise and healthy eating are important too.
Now more specifically, I want to let you know that finding a job is really hard, and it's not a negative reflection of you that you can't find one. I finished high school this year and am struggling to find a job - any job - to make some money. My parents, also being migrants, struggled a lot till they found a job because of a lack of experience in the country. The job market is competitive and that's why it's hard. So I know it's easier said than done, but please don't think it's because of your English or your skills or qualifications, and don't lose hope. Seek those work connections, talk to people and continue applying. You might get rejected many times, but don't lose hope. Did you know J. K. Rowling, author of the famous Harry Potter series, had her book Harry Potter rejected 12 times before she got it published?
You might find it helpful to contact recruitment companies to help you find a job. Write the best resume possible and build connections through social media and face to face.
I'm also sorry you've had a bad experience with your previous boss. Again, this is something I think you could address in therapy, especially to deal with your fear of having another bad boss. If it helps, not all workplaces have bad bosses - many are quite lovely - and your past experience is not reflective of your future ones. It might also help to remember that if you do fall in that situation again, there are measures you can take with your workplace to address bullying or any cause of concern.
As Haifa said, speak honestly with your girlfriend.