I am looking to get 275 cc moderate plus or 300 cc moderate plus. Will it be too wide for my petite frame?

Thank you for the question.  It really is NOT in your best interests to heed the advice of online consultants when it comes to be specific breast implant size/profile that will best achieve your goals.  Despite your good description of body type, measurements, and goals, online consultants are really only speculating when it comes to the best implant type, profile, and size…  Also, making comparisons with other women ( in regards to the size/profile of breast implants they utilize), is not as useful/relevant as you may think.  Generally speaking, the best online advice I can give to ladies who are considering  revisionary 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 are looking for. Ask to see lots of examples of his/her work. Sometimes, it is necessary to seek several consultations before you feel comfort will about your choice.2. Have a full discussion and communication regarding your desired goals  with your plastic surgeon. This communication will be critical in determining  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 "B or C cup”  etc means different things to different people and therefore prove unhelpful. Also, as you know, cup size varies depending on him who makes the bra; therefore, discussing desired cup  size may also be inaccurate. Again, best not to discuss your goals and/or judge the outcome of the procedure performed based on achieving a specific cup size. 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. I generally select appropriate breast implant size/profile after the use of temporary intraoperative sizers and viewing the patient's chest in the upright and supine positions.I hope this (and the attached link, dedicated to breast augmentation for petite patients) helps.

Without photos it is difficult to give you an opinion. Consider re-posting with photos. The 25cc difference will not be a visible difference. Consult with your board certified plastic surgeon. 

Is always best to follow the advice of the plastic surgeon that you have chosen.  Honestly in many patients the difference between a moderate profile plus and high profile breast implant is minimal and not very noticeable as I would not be concerned that you're going to project too much.However it is not a bad idea to consult another plastic surgeon for a second opinion.Having said all that I do not assess about the base width correlation with implant size and do not think having an implant 0.3 2.6 cm wider than your base width will be noticeable.