You are claiming these only:
1. 30 Aug to 3 Sep 13 - from developer
2. 3 Sep to key collection - from developer for the delay in handing over key, if they agree
3. From 3 Sep to 31 Dec 13 - from Iras for property tax rebate due to vacant tenancy
Write in to lawyer re 1 and 2.
Write in to Iras for 3 (I also have not yet written in for mine which was almost 8 months vacant.)
In any case you must have paid up the property tax already in order to do these claims from developer and Iras.
Hope you got these step by step sequence. There is no hurry to get these done cos there is no expiry date. I have even procrastinated more than 1 year previously.