Is Zakat obligatory on my money invested in a contracting company, given that I withdrew my bank balance four months before Ramadan to establish the company, and I have not yet made any profits from the projects?

Zakat on wealth becomes obligatory upon the completion of its hawl (one lunar year), and it is not permissible to wait for Ramadan if that is not when its hawl is completed. If the wealth falls below the nisab (minimum threshold) before the completion of its hawl, then no zakat is due on it.

Equipment not intended for sale is not subject to zakat. As for items prepared for trade (such as building supplies), zakat becomes obligatory on them upon the completion of the hawl of the money with which they were purchased, and items prepared for trade are to be valued at the completion of your hawl.

If the items you trade in reach the nisab and you do not find money to pay the zakat, it becomes a debt upon you, to be paid when you are able.