Hi Honeygal.
$22,000 is actually quite high considering yours is a 3 room flat. I suppose the bulk of your cost is on the carpentry. I did up my 3 room flat just like the way you did, by engaging various contractors i.e. electrical, cabinet, wet works, etc. However, I did buy all the stuff like floor tiles, laminates, sinks, cooker hob & hood, lightings, cistern, taps, etc. on my own and getting the respective contractors to install. After adding up everything, I spent about $15k including all the fixtures. I only hacked the wall between the living & dining plus kitchen wall tiles. Previous owner used rubber tiles at the living and bedrooms so no major hacking was done. To save cost, I overlayed the floor and wall tiles at the bathroom and WC. As for the bedrooms & utility room, I engaged Supreme Flooring which cost me $1.5k for the 3 rooms. My carpentry work is only the kitchen cabinet which cost me $3.5k including the solid surface top but excludes sink, cooker hob & hood. Main contractor did hacking, plastering, changing of water pipes, laying of tiles, bi-fold toilet doors. Electrician changed the wiring for the whole house including new DB and power, TV & electrical points. Carpenter did only the kitchen cabinet. I did the painting, which almost killed me..I had to do multiple coats becoz of the plastering!
Well, its probably too late for you do anything now since they have already started work and you would have signed on the quotation. Maybe you wanna re-look at your carpentry stuff again and see if you could bring your cost down. You can find nice readymade wardrobes and cabinets nowadays quite easily. The other advantage is that you can remove/change it anytime you want.
Anyway, good luck on your reno..its exciting but tiring especially you are the main coordinator. Some pics to share with you on what I did.