I just returned from a conference/research stint in Spain, and spent 8 of the 30 days without my baggage.
If I read you right, you did get the stuff back eventually, which means that it is unlikely you will get more than they have offered you.
When I was a poor young postdoc in England I used to fly pretty often between London and the US (where my now-wife was staying), and Pandemonium Airlines misplaced my luggage in London Every.Single.Time. usually for just 2-3 days. The compensation I got from them just about covered my annual clothing budget, which is why I continued to fly Pan Am by choice. - DvF