Do my nipples seem too far apart? If I have a 450cc-475cc implant, will it make my nipples further apart? (Photo)

Your Nipple/Areola is located where it is located.  An Aug will not change this.  Most every woman has subtle asymmetry...this is normal and nothing to worry about.  I hope that helps!

Every breast augmentation requires that you work with the patient's anatomy and their goals to achieve the best possible outcome using all of the most sophisticated modern techniques, technical skill and training, and years of accumulated experience.  No individual has perfect anatomy to begin with.  So your nipples are where they are.  They are not "too" far apart.  I would NOT have been concerned about your nipple position or the gap between your breasts, because with the appropriate skill and experience these issues would not present a problem.  If you have been told that your nipples are too far apart or that there is too wide a gap between the breasts, perhaps the surgeon was concerned about their own ability to give you the outcome that you deserve.  The skill comes in the ability to deal with the particular characteristics of your breasts to get an excellent outcome.  The size of the implant will not move your nipples in the way you are concerned.  If you have the operation performed through the incision on the chest wall along the lower border of the breast (inframmary approach; oldest, least technologically sophisticated method), however, you might end up with implants which are laterally displaced and too high because of the technical limitations of this approach.  If the implants are placed through the armpit using the surgical camera (transaxillary endoscopic approach), there is more control over the shape of the pocket and the space can be crafted under direct vision giving you an excellent aesthetic outcome.  The choice of the implant will be up to you.  If you try on sizers and determine what visually makes you happy, meeting your personal understanding of the perfect breast size for you, and then use that information with the surgeon to pick the implant which fits best on your chest wall, it will maximize your potential for a beautiful result.  Based on your wish pictures, it appears that 400 cc may be too small to achieve your goals.  It is very unlikely that 400 cc will make you a full D or a DD.

Thank you for the question and pictures. Based on your photographs (from what I can tell), I think that you are starting at a good place and should have a very nice outcome with breast augmentation surgery.   I also do not think that your "nipples seem too far apart". Generally speaking, patients who undergo breast augmentation surgery will have a slight increase in areola size: it's color does not change. Also, generally speaking, the nipple/areola complexes should remain "centered" on each breast mound after breast augmentation surgery.
Otherwise, unfortunately, online consultants will not be able to provide you with specific enough advice (regarding specific breast implant size/profile) to be truly helpful. Generally speaking, the best online advice I can give to ladies who are considering breast augmentation surgery (regarding breast implant type/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 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. In bra sizers can be useful communication tools also. I have found that the use of words such as “natural” or "D or  DD 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 the communication process.
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 ( after the use of temporary intraoperative sizers).
I hope this, and the attached link (dedicated to breast augmentation surgery concerns), helps. Best wishes for an outcome that you will be very pleased with.