Hmm ya that could be a few things, to start off F2P is always a higher bann rate compared to P2P, try to bot very short sessions with short breaks.
They seem to work the best for woodcutting.
Also getting 10 QP can be a nightmare in F2P, I know a lot of people who get banned when they bot the 10QP, it's something jagex really doesn't like.
But try short bot sessions with short breaks aswell.