Hi
It seems you have more upper body than legs. The good thing is that this will provide you with a low center of gravity which is good for aikido
Also since your weight indicates you are a bit round I would suggest going up a size rather than down. You would be happy about the extra width, and the extra length also come in handy if you have a long upper body. It looks really silly if the lapels under the belt are short.
I am roughly 190 lbs and 182 cm tall. I use a size 5 from Tozando. Fit's perfectly... however NEVER ever wash it warm or tumble dry it. It will shrink in both length and - depending on how it's weaved and sown - width.
I don't know what they will allow for you in your dojo, but I have a few karate gi's that I enjoy during summer. They are cooler, and they fit better around the waist.
But first and foremost: ask your sensei or your club mates. They will be able to help you.
Seek out someone of the same height and girth if possible, and ask what they use.
See you!
Jørgen Jakob