Although it is quite simple to do a basic conversion of your manuscript you need to ensure that you have met the Kindle Publishing Guidelines and have included correctly converted cover image and generated TOC and external NCX indexes. Then you need to check your file against as many devices that you have access to.

By having the same team do the editing and conversion you can have confidence that new errors are not being introduced.

Alternatively you can let us sort it out. We strip the file back to a clean html and then rebuild it using Kindle valid markup. A multilevel toc is built and used to generate the NCX before generating the Kindle file for you.