You're doing all right. If you cut through in a mix with your Cube, then you don't need to upgrade for the time being. Experiment with the sounds you get on that Cube, read the forums (especially basses and amps) to find out what people are looking for, hearing, and experiencing with their gear, and compare them to your rig. When you finally feel like you are ready to make an educated purchase, try to play the gear you are interested in buying in person. Every piece of gear I've been disappointed in has been one I bought cold based on hype, hope, or reviews.
You could start buying gear now (and that would probably be fun) but you'll save yourself a few bucks and some frustration by being just a little bit patient and letting your education catch up to your desire for tone.
Coming onto a forum and asking, "what do I need to be better" is going to lead you to one of two things; this thread where we all say, "I don't know, what do you need?" or a thread where everyone tells you what they use whether it helps you or not. A better way is to figure out specifically what you want to accomplish in your circumstance (e.g. I wanna sound like a tornado in Elton John's refrigerator) and then ask what you need to accomplish it, or to figure out what you need (I need an amp that produces perfect tube tone, weighs 5oz. and outputs 2000W) and then ask what gear can get you there.
Good Luck