Weight gain after fat transfer to breast, will my breasts disappear if I lose weight?

Hi I had fat transfer to breast 3.5 weeks ago. I was a 34aa previously and I estimate now a full A cup. I am petite and was slim, but with eating well,as advised, and not doing normal exercise my weight has increased to the heaviest I’ve ever been and I look it! I’m worried that once I start exercising and eating less, my modest increase in breast size will disappear. Thoughts, advice?