a-levels...

I started revising around mid march but this half term,I haven't been able to do as much revision as I wanted to.I enjoy what I learn but my brain doesn't feel engaged,I am not even experiencing burn out
I only manage to get a few half an hour slots a day but I planned to do hours.I even woke up at 2 am just to try and catch up but I was too sleepy.

I feel like I haven't done enough.

Exams are approaching quite fast, try to do at least four hours a day. If it is quite hard to get into habit, start slow then increase the pace.

That comment was on the assumption that you cant jump straight into four or five hours a day, if you really need to catch up, this is probably the right thing to do, try emailing your teacher and perhaps they can offer some advices too.