Started at size 4, skipped over 6 and now I'm an 8, but not on purpose.How do I maintain?

Here is my story and I'm sure I already know the answers, but I'd still like to hear your ideas. I've been maintaining at a size 4 for most of my life, easily, definitely does not mean I was in shape, but it was easy for me to stay there without too much effort. In the last year or so I have gained a lot of weight, blame in on entering the fantastic 40's, stress, being lazy and I'm sooo greedy. So obviously nothing fits anymore. I had to do some shopping and I'm a size 8. Completely skipped over a size 6. The thing about it is, I don't mind remaining a size 8 as in the right size clothes I look good. When I was still squeezing in my 4's I looked like a busted can of biscuits. I like this thicker more voluptuous figure. But outside of clothes or in a bikini I look horrible. Therefore I have started exercising again and trying to eat cleaner.

I'm worried that if I keep doing the right thing I might drop down to a six. I'm happy at the eight. I just need to lose the gut and the back rolls. I'm even okay with the size of my thighs, but they are flabby. I know I need to weight train and reduce calories to a certain extent and make sure my protein levels are adequate. Any other advice to keep my size up, but tighten this body?