#Talk to your DM
This is really the only viable solution other than leaving the table (which I'll get to next.) I wouldn't 'gang up' on the DM about this, but broach the subject with regard to wanting to better understand how they (the DM) is generating story and how much impact the PCs have on the world and how much impact the world has on the PCs.
##Session Zero Did you have a Session Zero to discuss the expectations from the DM and the players about how the game and story would run? If not, this is a great way to introduce the issue you and the other player are experiencing.
You can set this up with the DM by just stating that you'd like a better understanding of the world and their game and that there are some questions about it. You can also say that given the game has been going on for about 8 months, it's a good time to make sure everyone's expectations are being met. This includes the players expectations of the DM/game and the DM's expectations of the players.
##But what if there is no progress? Then you need to ask whether or not you are still having fun at this table. It is still possible to enjoy the table and the game even without your backstory or character growth. But if that isn't the fun you're having, then your only option may be to walk away - and that's okay! Everyone should be having fun at the table. It may not be the fun you expected, but as long as you're still having fun, then let it continue (You just may need to shift your expectations in order to do so.)