I totally understand the whole body image thing during pregnancy, but it's really not the time to worry. i Know it's much easier said than done. It sounds like you're doing the right things, smaller meals more often, healthy snacks. Just have loads of healthy things on standby to grab. Nuts and seeds and fruit are great. Also if you're craving carbs like I did, I always cooked up some bruschetta (toast some sourdough and cook some tomato, basil and onion up and put on the toast). Things like that are great.
i wouldn't be doing any type of weightloss, you never know what is in weightloss products, but it wouldn't be good for bubs.
Also pregnancy yoga is great and lots of walks and lots of water.
And after the birth you can concentrate on weightloss then. If you breastfeed that will help weightloss, and I find just getting up and down to bubs helped!! Enjoy they one time in your life that you have to be big!!! xoxo