2mm is very thin material to be welding with SMAW(stick).
With 2mm thick material you will get penetration no matter what setting you weld with, the highest amperage you can maintain an arc with and not burn through it what you should use.
On thin material use a low amperage setting, I personally have never even tried welding stick on 2mm metal, we always use Tig for stuff that thin. By increasing the arc length(moving the arc away from metal) you will increase voltage and reduce penetration, by having a short arc length(close to the metal)you will have more penetration and a more convex bead.
If you are worried about penetration look for the HAZ(heat affected zone) around the bead(will turn the metal different colors) if you see or the outline of the bead on the otherside of metal, you are getting penetration.
I suggest getting some thicker material, 3/16-3/8'' thickness for practice and then layering on that, or do fillet joints and just cascade out from the fillet. Stick is too hot for 2mm material.