Hi Andrea, I don't think your doing anything wrong. I am started to work with Gold myself, like you I been working with coper and brass for 2 years. The thing with gold, specially 14k, is that its hard, even after you annealing it, it does get a little softer after heating it up but it will never be as soft as copper, even copper after you hammer it hard, will still be softer than 14k.
the differences in 10k, 14k, 18k, and 24k, that I found, based on the research that I did myself, is that 14k and 10k, because they are mixed with other materials, they are harder than 18k and 24k which should be softer, I even read somewhere that 24k is not ideal for jewelry because its too soft. But don't quote me on this, I am no means an expert on gold, this is just what I learned from my experience.
I hope this info helps.