Anyone a bra size expert? 😂

Long story short for years I was a 38 D/DD but after 5 years of first being pumped full of hormones for fertility treatments, then pregnancy, a tough c-section recovery, and a year of breast feeding my body has changed. For a variety of reasons I’m not going to get measured by a “professional” so I’m measuring myself. I know there are 2 methods of getting your band size- under the bust +5 or over the bust, and then you take the full bust minus band size to get the cup. Problem is that comes out as 2 totally different sizes for me. Under the bust I’m 39” (so 44 band) but over I’m 40”. Full bust measures 49” so that gives me either a 44DD or 40I 😳. Are those basically the same because the larger band allows a smaller cup? And if so is it likely a 42G (split the difference) would also work?

And yeah, I know I could buy and try different sizes, but all of those are hard to find, and returning is a hassle so I thought I’d ask if anyone here has insight. 😊

TIA