There are many different tools that you can use for free to help you and your team collaborate, create tasks, and measure progress.

Here is a list of the tools that I have tested with clients and used myself:

Workdo
Eko
Flowlu
Bitrix24
Asana

I have personally used all of these tools and am not a huge fan of Trello.

You can play around with all of these tools free of charge for small teams. I think one of them may work better than Trello for you and you will not incur any costs.

Each has their pros and cons but for the most part have similar functionality. I hope this helps!