No you don’t need a bigger base. I can load up some Tangiers on a Mya Petite and still get more clouds than my friend smoking their KM’s with King Moassel.

Question is what tobacco are you using.

I have never been a fan of the vortex, It’s a great concept, just poor heat retention. Unless you are smoking Nakhla putting 2 Cocos on a Vortex and char the tobacco and make it harsh.

Typically for whatever your smoking on a vortex, i would cut your cocos in half. I use Craftsman Handi-Cuts but a small knife and tap from a hammer does the same thing.

Then use 3 halves placed in a triangle pattern. Pack a little more tobacco than you are unless you are really packing it in there.

On the Mini Mya I would fill the water to just above the second beveled row from the bottom, too much water will reduce your smoke. To little will be too harsh.

The only other thing I could think to suggest is a Heba Diffuser. Breaks up the smoke and makes the clouds a little bigger but not a whole lot but it more noticible on smaller Mya’s
http://www.hookah-shisha.com/p-1341-heba-diffuser-hookah-smoke-diffuser.html?idaffiliate=284