Technically if you sold some of your art, your a professional. :wink:
I understand what you mean, I earned money from my work for more than two years before I felt like I was really getting somewhere.
Your animations are really good and you clearly have working knowledge of the principles of animation, the secondary actions is the most notable, it's very hard to believe that your a amateur at this.
When making assets to sell to game developers I browse Steam greenlight, you can then see what developers need directly. Use the developers for inspiration.
As a artist you will often be forced out f your comfort zone, so I will recommend learning 3D animation. You already have a huge advantage in the fact that you know how to do animations, all you will need to learn is the different mechanics from 2D to 3D.
As for using Blender, I will recommend it before you go and buy expensive 3D software. Blender isn't the best tool for animations, it's one of the software's largest shortcomings. However as 3ds Max is expensive, especially if all you need is it's animation tools.
I will recommend using Blender until you can afford other software, even if you are a secret millionaire I will still advice you to give Blender a try. The difference between Blender and other software isn't worth the large price gap, especially because Blender is free and Max cost an arm and a leg.
Blender is also updating and improving, the more people support it the faster it will grow.
Here is a image of some motion capture data in Blender, as you can see it's similar to Spine with a extra dimension added in.