Lost in the requirements and unable to estimate – advice appreciated

So this is my situation: I took on to do management software for my company in January. I am not a developer, so I hired a front-end and a back-end person on an hourly basis, provided them with a work flow document and high-level requirements and up we went. According to some consultations I had prior to this, the project should have taken 6-8 months to complete. We are now 11 months in and I have no clue where we are at and how long it may still take to finish.

I believe my inability to write detailed step-by-step deliverables make it very hard for the developers to give me time estimates. Weekly meetings to plan the next steps haven't helped. Developers estimates were broad, and unsure whether they are lost themselves.

I am considering getting an outside company to take a look in the code and guide me into the open deliverables and give me estimates on built time. This will probably cost quite a lot, and we are already waay over budget.

Any insights or tips are greatly appreciated.