About your choice.
Well, on the one hand, speech pathology is very likely the better career. Lots of kids need speech pathologists, and it's going to become more common as parents spend more and more time with their cell phone and less and less time playing with their kids. I know some parents who infuriate me with their cell phone habits, it made a lot of sense that their babies were speech delayed. So given that, I think that you made a good choice.
But Canberra is not boring and it's really blossomed in the last few years. Having traveled to many places, I can tell you that it has a lot of good food (which is important to me), and in terms of what would matter to you, a great fitness scene, tons of cross fit, yoga, dance, etc. The Kingston and Lonsdale areas are fun for small boutiques, etc. There are several wineries in the area, and Bateman's Bay makes for a good day trip.
One advantage that I'd give Canberra over Sydney and Melbourne is that you can spend less time in traffic. The city is spread out and the roads are wide. Everything in Canberra is 20 minutes from everything else, and it's a relaxing 20 minutes, not one filled with endless stopping.
As for it being cold, I'm from Montreal, Canada so you're sounding like a wimp