Hello,
My name is Alex and I'm a second year Psychology student at YSJ. I took A-Level Psychology (specifically AQA) and if you have any questions I'd be more than happy to answer!
Firstly, GCSE Psychology is different to A-Level Psychology. GCSE is very structured and minimal, and you learn very basic (and sometimes boring) research, that's not too relevant to day-to-day life. A-Level takes a bigger focus across a range of psychology subjects, like research, social psychology, relationships, mental health, biopsychology etc., but this can depend on the college and exam board, so I would look closer into what this specific course has and whether its something you would be interested in.
Interest sometimes can be the difference between remembering or not remembering content. I had a huge interest in Psychology to the point I continued to do it at degree level. I would not have gotten an A* if I was any less interested in the subject, because this interest fuelled my motivation to study every day. Maybe you could find some example content/homework from the different subjects and give them a go at home to see which one you prefer.
Think about how you prefer to be examined. Are you a confident essay writer or do you prefer short answers and memorisation? Do you prefer exams or coursework? Maybe compare how the two subjects are assessed. I know you mentioned English isn't your favourite - in my experience, Psychology does have a couple of analysis questions where you might be expected to draw on English skills, whereas the math content is more along the lines of graphs and charts, with some equations (mostly in the research module).
Overall I would recommend talking to the careers counsellor at your school. A-Levels are crucial if you want to go to university, so the subjects you choose now might limit the subjects you can go on to study. Once you have an idea of what you want to do next, it might make the decision clearer.
Hope this helped

-Alex, Student Ambassador