Attiny85 not able to understand data from 433Mhz using VirtualWire.h
Have you tried using the Radiohead  library? I know you said you tried different versions of Virtual Wire. The RH_ASK class works on a 328p and a nano for sure and they claim a simple Rx program can run on a ATTiny85. They have documentation under RH_ASK regarding the changes you need make to the library.
Another possible fix is to edit the Virtual Wire library files, they might have variables like "Max_payload" (Radiohead does) whose size can be decreased. 
I haven't actually read the Virtual wire library, but I am sure Radiohead should fix your problems.

If this doesn't work, do you have an oscilloscope? Maybe we can try debugging it like that.

Edit: Maybe try commenting out the vw_set_ptt_inverted line first. I don't think you are using the DR3100. Might not make a difference because you haven't actually set a pin for ptt.
Next thing you can try is just connecting the data pin of the Tx to the Rx. You should be able to check if the module is actually connected to the ATTiny with this.