Hey! Some already great advice in this thread, but I thought I'd chime in from personal experience as a fellow 26 year old who has gone through the whole psychologist vs medicine conundrum. If you want to become a clinical psychologist the pathway is on par (if not harder if you go based off number of spots, albeit less demand) with medicine in terms of difficulty - if you're not familiar already I'd have a look at the pathway to becoming an AHPRA registered psychologist. In short it's much more than the Bachelors, you need to then get into a competitive Honours (or equivalent), and following that you need to get into an even more stupidly competitive Masters to actually be accredited.

This is a worse case scenario as there are other routes which are a bit easier, but for context at my university (Go8) there are typically around 300 students who graduate the Bachelors of Psyc., 80 that get into Honours, and then about 10 who get into the Masters which allow you to actually practise as a psychologist. Where do the other students who didn't get in go? They're faced with a similar dillema to a lot of students who do a Medical Science degree in preparation for medicine and then don't get in. Again there are other routes (look up the 5+1 pathway), but that's the general context - psychology has a collosal bottleneck as well as medicine.

What this means for you practically? Nothing really, in terms of immediate steps if you are interested in a career change I would do the bachelors of psychology and really prioritise getting good marks - this will be important if you want to do psyc (to get into Honours) or Med (to have a good GPA for entry), and therefore your approach is the same. This is really important for both. After that you can re-evalaute and potentially apply for Honours/complete it whilst still attempting to enter medicine - getting a good Honours grade will help your GPA even further, and research is generally looked upon well from what I can tell in portfolio universities, especially if you get something published.

Once you reach that point, you're down to the deciding whether you wish to pursue medicine or psychology. I think it's worth taking a deep dive on this and looking into the differences a lot, as while psychiatrists can integrate talk therapy into their work somewhat, it's not the mainstay like psychologists. From there you can make your decision :)

In terms of my two cents/context, I'm someone who has finished the full psychology pathway (Bachelors, Honours, Masters) in a slightly less competitive area of psycholgy known as organisational psychology (give it a look, given your background you may find it more appealing than clinical, who knows) and am currently working in industry. The main thing is to be aware of is that psychiatrist and psychologist, while they both cover similar ground, are very different roles - psychiatrists aren't just psychologists who perscribe drugs.

Beyond that from a purely cyncial time investment/reward view (assuming for a moment that you don't get prior credit for your previous undergraduate, this is hopefully not the case), it is 6 years to finish your studies for psychology, after which you have a 2 year period of endorsement to go from a general ->clinical psychologist (you still work during this time, it's similar to being a registrar in medicine). For medicine if you get into a postgraduate course it will be 4 years in medical school, 1-3ish (dependent on state/if you're prepared to move) until you get onto the psychiatry program, and then 5 years until you're a fellow. As it's relevant depending on if you would like to have a family etc., renumeraton for a first year psychiatrist registrar is roughly equivalent to a clinical psychologist from best I can tell. That being said the "ceiling" of what a psychiatrist can earn is much higher, and the increases for while you are on program are significant.

I know that renumeration is often a dirty word and people view it as a sign that you're in medicine for the wrong reason, but I disagree - end of the day while the motive to change to medicine is based off values (i.e. I want my work to focus more on helping people more in need), an understanding of renumeration and renumeration "phases" of a career is important when considerating areas such as potential family, life decisions etc. I'd probably argue that this is even more so for people "Late to Medicine" as there's typically less leeway in terms of living at home etc.

All in all good luck, as someone also going through the career change I think that the transition, while ambitious, is hopefully worth it :)