695cc, 745cc, 800cc Natrelle hp silicones, is there a big difference between them? (photo)

All of the sizes you mentioned will certainly provide a significant increase in implant size. Your Plastic Surgeon will measure you to determine the best shape, size and placement of the #implants to be used. Lastly, another important element to a satisfying result of your #augmentation is realistic #expectations.Here are some helpful guidelines to consider for sizing: Usually if a woman wears a size 36 AB bra and would like to be a C cup, which is the average size that women wear and the average size bra that is sold, she needs a volume of approximately 350 to 390 cc to make that change. This becomes less if she's wearing a 34 bra, because it has a smaller strap size and the cups have a smaller diameter. A smaller diameter implant would then be a volume of approximately 300 to 350 cc. In the same way if she was more petite, maybe a double zero or size one and wore a 32 AB bra, then to become a 32C cup she would only require about 250 to 300 cc. This is a general number, and of course there are other factors that will affect this. Other factors which contribute to the outcome are #size, #shape, and #profile. You should also keep in consideration, by #increasing your implant size, the #pocket may require adjustment and a lift may be necessary; to better #support the new implant. Additionally, a mesh for further support may be helpful depending on the #implant size and skin #elasticity. 

I would suggest visiting with your surgeon again and discuss the options of sizes. All three choices will be a considerable difference from the 450 cc implants. The chosen implants are very big and heavy, and may give some discomfort in your neck and shoulders. Your surgeon can best guide you as to the size that your frame and tissue can support.

Choosing the right implant for you requires an exam in person.  I can not tell you what might be right for you without the exam. Best of luck.