Software for a consulting company

I am looking for a software developer to create a custom software solution for my consulting business. The software should include features for client management, project tracking, and invoicing/billing. No existing software needs to be integrated with this project, as this is a completely new software design. I am expecting the timeline of this project to be between 4-6 months. The software must be reliable, intuitive to use, and well-documented. Additionally, excellent ongoing support after the completion of the project is essential.