I have to agree, I decided to be professionally fitted for a bra. I walked in wearing a 38A which I've worn for 40 years and walked out wearing a 36C. I now no longer rip my bra off the minute I walk in the door which I've done my entire life, now my bra fits properly, I look better in my clothes and my bras are 100% more comfortable!
I have heard numerous times over my 50+ years that over 80% of women wear the wrong size bra! I highly recommend you get fitted regardless of your weight at the time. You can go to Nordstrom and they have trained, professional ladies that will fit you, it's free and they don't pressure you to buy anything. If you don't have a Nordstrom near you any upscale department store that has a lingerie department should have trained professionals to fit you. I can't imagine you regretting it!