Is a 275cc implant too big?

It is difficult to answer this question without the ability to examine you . There are several ways, however, to help determine the ideal breast implant volume for you.  Many offices will offer computer 3-D imaging.  This is a great way for you to get an idea how you will look after your breast augmentation.  It is a good way for you and your surgeon to communicate about what is best for you.  Preoperative use of external breast sizing implants is also a good way for you to communicate what size you would like to be.  Both of these techniques allow your surgeon to determine whether or not these are appropriate sizes for your particular breast.

  The average volume for a breast implant in the US is 350 cc, so 275 cc is not a big implant.  Always try on sizers in the office and get the input of your surgeon.Kenneth Hughes, MDLos Angeles, CA

Thank you for the question. In regards to specific size/profile of breast implant, despite good intentions, online consultants will not be able to provide you with  meaningful specific advice.  Ultimately, in person consultation with well experienced board-certified plastic surgeons will be necessary. Careful measurements, dimensional planning, and careful communication will be key.
Generally speaking, the best online advice I can give to ladies who are considering  breast augmentation surgery ( regarding breast implant size/profile selection) is:
1. Concentrate on choosing your plastic surgeon carefully.  Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you're looking for. Ask to see lots of examples of his/her work.  
2.  Again, have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining which operation and/or breast implant size/type/profile will most likely help achieve your goals.
In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or "C or D cup" or "too big" etc means different things to different people and therefore prove unhelpful.
 Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup  size may also be inaccurate.  The use of computer imaging may be very helpful during this communication phase.
3.  Once you feel you have communicated your goals clearly,  allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals.  Again, in my practice, this decision is usually made during surgery.  The use of temporary intraoperative sizers with the patient in the upright position makes selection of the best breast implant size/profile relatively easy.
I hope this, and the attached link, helps.