B.E.B!
You just described my world to a tee, with the exception of the test fees.
I always charge for LPCs but vary the amount depending on whether the candidate is in one of ours, a private owner or (rarely) has rented from one of those non vat competitors. (Quite often they end up not being properly insured and even those reluctantly rent from us.)
I agree with other posters - you need to increase your fees - I rarely do any flying for free. The main exception is renewals for my instructors.
I always explain why my fees are what they are (cost of AOC every 3 years and all the things you mention) and how little I earn per year. Reasonable folk understand, the others I'm not interested in anyway!