Basically I want to know if once I submit the micro patent form, is my invention protected if I start selling it to companies?
The only "micro form" I know of with the USPTO is the form/checkbox to claim micro-entity status to get reduced fees. I assume you are talking about the filing of an application. Once you file an application, either provisional or non-provisional, you can disclose your invention and not break novelty. For the U.S. you have a quasi grace period of a year so you could have chosen to disclose a year before filing. It is not generally recommended and any disclosure before filing will keep you from ever getting any protection other than in the U.S.
It may be that your application is not detailed enough or has some other problem such that selling your product effectively discloses something you would like to have patented but is not covered in the application you filed. In that case you might need to file again and rely on the grace period - US only.
Any real protection only comes after a patent is issued. Up until then people could gamble that you will not get a patent and start copying your product.