A few more suggestions:
1. I went to a lot of trouble to cook the meal …
- but to no avail …
- but I shouldn't / needn't have bothered, …
- but it was a (complete) waste of time …
- but it wasn't worth the effort …
… because no-one ate any of it.
2. I got everything spick and
span
- but to no avail …
- but I shouldn't / needn't have bothered, …
- but it was a (complete) waste of time …
- but it wasn't worth the effort …
… because it soon got dirty again.
3. I really busted a gut (on/with that)
I put in such a lot of effort (on/with that)
I worked so hard (on that)
- but to no avail .
- but I shouldn't / needn't have bothered.
- but it was a (complete) waste of time.
- but it wasn't worth the effort.
- but nothing came of it.
4 . (VULGAR) I worked my bollocks off for sweet FA. (FA – Fanny Adams /
fuck all = nothing at all;)