Disclaimer- we're not doctors. Listen to your doctor about surgery prep and post surgical care. Buy new bras when your doctor says you're healed. This is a bra fitter's perspective not medical advice.
Almost every day, women come to us wanting push up bras, more lift etc. It doesn't matter the volume of tissue they started with- it's a nearly universal desire. We are all for breast augmentation. If you want it, go get it. We'll be there to support you once you're healed and ready to shop in your new sizes.
Two things to consider though:
Often (not always), the right size and style of bra can address many of the reasons you're pursuing augmentation in the first place.
Your doctor is not a bra fitter. They work in CCs of implants and those don't translate to specific bra sizes. Take any advice about your final "size" with a grain of salt and know the limits of bra sizes.
Let's dig a little deeper.
If you're seeking augmentation because you've had kids or weight change and you are seeking lifted perky breasts that's great.
You can also achieve lifted perky breasts with the right bra- one that's tight enough in the band and has a seamed cup that shapes your tissue. One caveat- your breasts won't be lifted when you're braless. Again, get the surgery if that's what you want, but perhaps try a different bra first.
If you're small breasted, know that most of the larger breasted women we help want what you have. That doesn't change how you feel about your breast volume, but the advice above helps here too. I have bras in my wardrobe that are just comfortable but do very little to lift and augment and ones that gather all my tissue and move it up and forward. You don't need a thick push up bra to achieve that look, even with smaller volume.
Augmented breasts are great. They do come with their own unique bra fitting challenges, mostly that they don't move on your body like original breasts do. Depending on the rest of your frame, it might limit what styles of bras fit you.
Which segues to the second point. I'll be the first to admit I have a limited understanding of what 800ccs looks like. We rarely talk about the specific implant sizes in the fitting room, we just dive in. But your doctor likely has a limited understanding of what a 32DDD looks like. It's likely your doctor has a limited understanding that a 32DDD and a 42DDD are not "the same"- the 42DDD is going to have more overall tissue.
I'll never forget one of my first augmented customers. She was tiny around- I believe she measured 25". Her ideal bra size would have been 26KK (UK, so P in US). 26 bands are tricky enough to find (there are a few companies) so she was already shopping for 28K (exists, but harder to find- we have some!) or 30JJ. The 30 bands are now 4" bigger than she is, but her bra choices were greater. She said to me- "If I understood bra sizing before my surgery, I would have opted for 100ccs less in each breast, been just as happy with my overall look, and been able to shop for bras in twice as many places for much less money."
I'll never forget that perspective.
So the point of all this is go see a professional bra fitter at a fitting boutique (like us!). The ladies at department stores and big box retail are lovely, but they can only sell you the limited sizes and styles they have on hand. If you're considering augmentation for volume, come try on some full bust bras and invest in the one that's the volume you want. Understand how that volume will sit on your chest. Bring that to your doctor and see how close you can get to that in CCs. Know your band size- larger breasts need a tighter band, though augmented breasts come with their own support for a while at least (meaning she could get away with that 30 band on her 25" frame). If you're looking at augmentation as a breast refresh, come try on some different sizes and styles and see if you can get where you want without the surgery.
We are not here to talk you out of surgery you want. We're here to help you go into surgery fully aware of the things to consider that your doctor probably won't. Doctors aren't bra fitters. They might tell you "you'll be a DD" but when you come to see us a 30G really fits best. That doesn't mean your volume isn't just what you want, it means your doctor failed to consider the importance of the band size in the ratio. An 30G and a 34DD are the same cup volume, but you'll want the 30 band for support and to keep the band from riding up and the straps from slipping. Understand the limits of the bra sizes (band and cup) available in the styles you love.
However, in the end, how you feel best in your body is what's most important.