An experienced 70kg rider i'd be suggesting a 130x40-42... not that i'd be telling an experienced rider what board he/she should be using.

Kit33r is right. The board isn't the cause of the problems, but it might be making it difficult to progress and learn to control the power. If you've got the money then buying a board the size you'll end up wanting to ride isn't a bad idea, but don't expect it to instantly solve your issues.
Sounds to me like you need to improve your board skills and learn to hold down more power and edge harder.