I am just looking at the design on your body and thinking up ideas for your next costume.
The neck line does nothing for you. You are not showcasing well developed pectoral muscles or big fancy tribal neckwear. The black actually minimizes the size of your chest. The top shoulder fabric looks narrow for you.
The shoulder of the sleeve looks small and fitted (opposed to having some volume to it). The sleeve then gains volume to create the 3/4th length puff. I think this makes your arms look short and draws attention to your arms and hands being thick.
In contrast to your narrowed upper body, your pale white stomach sticks out much larger than your upper body and hips. Therefore the main focus on this costume is pointing out that you are less healthy than what a doctor would recommend.
I think the flared pants are great. The mermaid aspect gives a great shape. Putting the colored flair on it is great. Using color is very important aspect of drawing people’s attention. Good work.
Recommendations
Arms: I would try other sleeves that make your arms look elongated.
Here is a sleeve of mine that has some volume to the shoulder and continues to the wrist. It is not as full as some sleeves, keeping a slimming look to the arm.
http://www.shakemyday.com/photos/costumes/c05.jpg
Neckline: I would make the neck line narrower as to not point out the fact that your pecs are not defined. There are some really wonderful neckline designs in folkloric dress with exquisite embroidery that will bring interest to your neck line and create visual volume.
Belly: You are stating clearly you are not interested in fully covering it. That being said- I have seen some amazing tribal and Indian designs that bring shapes down from the top on to the belly which breaks up the strait line across- so that it isn’t just a big white belly mass. Off hand I cant find a photo of those- but here are some other smaller belly drapes that break up the strait line and you could modify it to suit your proportions:
"Birds of Prey: Bellydancer" “Gothic Bellydance” posters
http://www.bellydanceposters.com/
You could mirror the vshaped neckline and a vshaped belly drape and vshaped belt, vshapes in your wide legged pants- which would make a very slimming visual line.
It is about what creates the most flattering body lines.
I look forward to seeing what creative inspiration you come up with next!