Psych is awesome.
Bsc-psych is the same as ba-psych, but you need to so some of the 'hard' sciences (chem, physics, bio, etc), whereas in the BA you don't. Otherwise, they're identical, coursework wise. B-Psych requires you to do MORE psych than the BA/BSC. See the handbook.
You've got stats, so don't change to avoid the maths (though you're doing appfin, so maths probably isn't an issue). If you're interested in becoming a psychologist: you need to do hons/pg-dip, AND two years of supervision (or preferrably, as things may change in the near future, masters (2yrs coursework)/doctrate (3yrs research). PHd does not count). By law, you need any/all of the above conditions to call yourself a 'psychologist'. Hope that made sense.
Psych is pretty generalist if you don't become a professional (i.e. steps in paragraph 1). It's very finnicky about somethings (i.e. research methods, making logical conclusions, and referencing), and gives you some great skills (logic logic logic & research) tht other degrees (i.e. BBA, from my experience) don't go anywhere near. BUT, it's just a glorified arts degree, out in the real world, without those extra years of supervision/masters/doctorate.
It's the wrong degree to do if you're doing it for the money... though organisational psych and its variants are paid pretty well, I believe (not as well as appfin grads are though!).
Content is awesome, personally, but some people hate it. Compared to appfin/accg/other-numbers-mathsy-things it might be considered a little 'wishy-washy', or more qualitative and interpretation-based. You can't do psy units from the appfin degree,
Unless you get special approval: talk to the psych department and get this, to try it out. Explain you're interested in changing over but don't want to until you've done at least one unit (i.e. psy 104 or 105, depending on your semester), and they'll probably give you the special approval (I've processed them in my paid roles at uni, so I know they give them out to people not in psych degrees.)
...any questions?