If you are not sure whether she hit you or whether you just fell (and if you cannot remember) then I would be inclined to drop it. If you arent sure, then the Court cannot find for you on the balance of probabilities (which is the level of proof required). However, I would take your solicitor's advice.
Ignore the fact that the police did nothing. They are only interested if they can prosecute. Whilst a successful prosecution would be extremely helpful to you the lack of one is neither here nor there.