It sounds to me like you just haven't had enough time behind the wheel. Not making cars behind you break hard and knowing which gaps are big enough etc only come with practice. If you aren't driving outside of lessons at all and you've only had 33 hours of lessons then I'd say you just need more practice, either lessons or out with parents just to get you more used to making the decisions, and the right decisions of course.
Don't give up ^_^