Am I too small to have 350cc Round HP Implants? (Photo)

Thank you for the question and pictures. Base on your photographs, you are starting at a great place and should have a very nice outcome with breast augmentation surgery.  However, 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 are looking for. Ask to see lots of examples of his/her work.
2. 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" 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.
I hope this, and the attached link (dedicated to petite patients), helps.

The exact implant choice depends on your "goal look". There is nothing intrinsically "good" about one implant size/profile versus another. It depends on how you "start" and how you want to "finish". Your surgeon should be able to choose the proper implant dimensions to meet your desired end result. Your "anatomy" can certainly accommodate it. Your nipples will remain fairly far apart as that is where they "live", but to my eye with properly placed and wide enough implants you should be able to achieve good, but not "touching" cleavage.