I am 20 years old, 34c cup at VS and my breasts are saggy. Will 350cc be enough or will it be too much? (photo)

Thank you for your question and pictures
In my opinion the surgical plan( uplift and 350cc implants) seems to be reasonable but is impossible to predict your final result without a face to face consultation.
Best wishes on your operation
Kind regards
Mr Giorgio Netri

Thank you for your question.It is important that you discuss this with your surgeon who may try some sizers. Based on your photographs and recommendation of your surgeon, the size of implants appears to be fine. This procedure needs a lot of experience and nothing can be said for sure unless one examines you.All The Best !

Too much? is not a simple question to answer.
When sizing patients, there are a number of useful tools including:
-3D imaging (has the added benefit of offering a volumetric analysis of the pre-operative breast)
-Breast sizers (rice bags)
-Goal photos
I also recommend that patients commit to a particular look rather than a cup size. Once a patient settles on a look that pleases them the overall cup size increase becomes less relevant.
With regards to your specific question, the key to obtaining a natural result is to stay within the parameters defined by your BWD. This will ensure that you avoid the dreaded "fake" look. In my practice, I will narrow candidates down to a range of implants which fit within their measures and with which they would be satisfied. A final decision can be made intraoperatively. 
I would recommend discussing your concerns with a board certified plastic surgeon (ABPS

It would be very hard to determine which size would best fit you without an in-person examination. The implant size and volume usually depends on your breast wall measurements, your tissue elasticity, and your desired results. Also, implants of the same size would look different on each patient so your surgeon would be your best resource for information regarding implant volume. 

Thank you for your question. The dilema in breast lift with augmentation is that you are performing 2 procedures with oposing forces in the same setting. The lift will tighten the breast while the augmentation will tend to expand the breast. This puts some restrictions on the implant size. The smaller size you use the less the risk of problems. There is no definite answer to this and many decide to do it in 2 separate procedures in order to minimize the risk as much as possible. My approach invloves a very conservative augmentation and to use 3d imaging and real life simulation in order to choose the safest implant that satisfies the patient's ambition. My advise is to go conservative and think carefully before you make any decision.Best,Shady Hayek

I think 350cc is a good volume for reshape your breast and achieve your outcomes as long as a breast lift be made as the virtual result shows