Can't really compare them as they're two distinct fields and I guess depends on your interests/passion. Commerce is arguably more flexible with there being a multitude of different fields you could major in and work with, but you're gonna have to work really hard on networking etc. Optom is definitely more limited career-wise and currently there is a bit of oversupply unless you go rural, but if you're willing to work hard, you should be fine either way.
I feel disadvantaged in Optometry as i've never done Physics, Chem or Maths
Most of people who I know who did optom last year only did 2unit maths, bio, chem. HSC Physics is pretty useless and doesn't help much in engineering subjects either.
It is a science-elective heavy subject no doubt, so be prepared for labs etc. Most courses such as babs, everyday physics, maths1031 etc. are meant for beginners and HSC isnt that important (though 2unit definitely helps for maths). The only subject you may struggle with Chem1a/b, which i think they do recap the HSC content quickly and it is assumed, so you could try your hand at a bridging course OR ideally just borrow someone's notes and learn what you can during the holidays.
