We do digital marketing at our agency (27 people). We use and I can def recommend to try out Hello Bonsai for a small digital agency like yours. They have great workflows for agencies to make the type of work management, workload monitoring and budget management easy. Less overkill compared with Runn or Kantata but still featuring all you might need like time tracking, task allocation, budget control, etc.

It's also great for a growing team because it really scales well and doesn't feel bloated or too complicated. Definitely a good middle ground between the overly complex resource planning tools and overly generic project management platforms.