It's easy for things to get convoluted so I always reconcile them and keep a spreadsheet.  With the market volatility from the past few years there may also be wash sale adjustments floating around that nobody is tracking.

With RSUs, the W-2 income is from the vesting, it has nothing to do with sales.  What I usually see are lots such as 5 shares vested, 2 shares withheld for taxes and 3 shares delivered to the broker.  So the W-2 has the income from 5 shares but the broker only sold 3.  So I always track everything per share and follow the money.  A year-end paystub may also be helpful.

Rick