GPIO output corrector
I think your circuit could work, but only in a few selected cases.

You have to take into account, that your Fets have a \$R_{{ds}_{on}}\$, which will influence the output voltage if significant current is drawn by the load.
Hence you will encounter a voltage below 3.3 V depending on the load.

I recommend using a voltage reference with a reference input like the TLV431.







simulate this circuit &ndash; Schematic created using CircuitLab

This allows a rather precise voltage output, which is much more stable. Capacitors are omitted, please look up the application notes in the datasheet. Also, as soon as you have knowledge about the impedance of your load, adapt R3 to your needs. 

If you have the money, there are references with an additional enable pin, which could save you some of the external discretes.