I'd argue psychology, when I did it with the past Study Design, it was indeed a very soft science. If they made it more of a neurobiology class, yes, it would be a science. You are learning how to conceptualize certain mental processes and have a descriptive means of going about studying "mind" - which will not be elucidated very well in the psychology course; you will learn more studying the philosophy of mind in Philosophy.
Firstly, if you dislike the subject, you will most likely do poorly in it. Personally, for me, it was all common sense and I bullshitted all the way through the course and got A+s all year in SACs. Exam time, I had not prepped and bummed out on the exam despite scoring a boderline A. I did not get a crash hot Study Score. Psych is very competitive and requires full/nearly full marks to get a decent score. Same with HDD. Have you studied HDD before? If not, borrow someone's text book and give it a read over. I have never sat the subject, but, from what my friends have said, it is much like Psych with re: to Study Scores.