Thanks for the feedback Jonathan.
I completely agree that I'm used to applying a lot of pressure when shaving with my Mach3 cartridge or straight razor.
I will send my straight to a professional and hopefully it will fix the sharpness.

In the meantime I will have to be less impatient with the DE. I even cut my finger quite badly while fiddling with the adjustable angle with wet hands.
Very very sharp DE blades from Merkur.

I also find DE's much harder to control than a straight. There is not much freedom in choosing the angle, and not enough tactile feedback in my experience.
It may have something to do with the weight of the DE I'm guessing.