First time entrepreneurs usually confuse equity with control, there can be dozens of mechanisms, by which VC's can gain control of a company they invested in.

A few examples:

* Controlling all C-level positions, firing you at will (which will affect your vesting schedule) * Controlling spending which will force you to raise further rounds, further dilluting you * Board seats * Veto power for exits

Get a lawyer and read everything a dozen times...