Yes, you are considered morbidly obese, with a BMI of 39.6.
It would be ideal if you could lose weight -- probably best to go to 200 - 220. However, you note that it may not be possible but would like some improvement in your chest.
There is something called "compromise" surgery. It can be done with minimal scars and it will only shrink, but not eliminate your breasts. There will still be a fold under the breasts but the entire chest will be smaller. This may be of help to you -- you should discuss this possibility with your local plastic surgeron.
Dr Jacobs