While you should avoid applying undue pressure I think you do need to sort out your shyness and get some clear understanding of how you both feel sooner rather than later. She needs to know that you are not happy with the current situation and why, and you need to know for certain why she isn't very interested in sex at the moment. You may be right that it's a body image thing but it sounds as if you are just guessing. One good soul-searching conversation does not constitute undue pressure.
While giving you partner time and space to sort things out is good you need to guard against it being an excuse for inaction because you are shy. It's all to easy to go along for years with an unhappy situation because you have been living with it for so long what does another day/month/year matter? And then it's all the more difficult to have the right conversation because your partner wonders why you are suddenly talking about a problem when you never mentioned it before and they come to the conclusion that it must just be because you had a bad day and dismiss it without realising you are actually talking about having had a bad decade.
We have a wonderful relationship now and as I always say I regret nothing because what I have now is the product of all the events, good and bad, of the past. However, were I to have my time over again, I would not sit for years in silence hoping for things to improve. They only improved for us when the plain speaking started.