Both peat moss and vermiculite retain water, so I wouldn't add any more of that if you are having drainage problems. Maybe more perilite or sand or small pebbles... Looks like a lot of peat in there.

It looks like you might be using Pro-Mix, basically a milled sphagnum peat and perlite mixture. I use it in small containers that easily dry out, primarily for starting seeds.
I would normally mix around 1/3 - 1/2 pine fines with it if I used it in a large pot. Just don't over water. Unless water sits on top of the mix for a lengthy period, I think the drainage is okay. A big problem with this mix is shrinkage as it dries. It dries on the outside first and pulls away from the container, so water runs through but doesn't get to the plant. Once peat dries, it doesn't absorb water that readily, so keep the top of the soil mix well cultivated.
Ed

After talking to the Stamiles who grow all their new intros in pots, I changed my potting mixture to contain half pine fines and half potting soil. I found the shredded pine bark mulch (some call it pine fines) at Home Depot. It allows for better drainage. I believe it is a professional mix, I forget the name of it. I had noticed that my potting soil had become compacted in many of my pots and they weren't doing as well as in the beginning. They also use Nutracote 13-13-13 plant food which lasts for 9 months. The plants I get from them are huge so I am currently using this mix as well as gradually repotting all my pots. Ugh what a job. I am still using potting soil for my seeds in their little baby pots though.

Dot