What size & type of implants are right for me?

I use a technique called dimensional breast augmentation which involves taking in a number of factors and measurements, so each patient is unique. That being said, given your height, weight, and your activity level, along with the fact you are considering a lift, I would say you are probably not that far off in choosing an implant in that range. Best thing to do is to see a qualified plastic surgeon that has good breast expertise.

At size 34 A each 100 cc’s of implant corresponds to 1 cup
size change. To achieve a full C would
require 200 cc implants. I always
recommend small round textured silicone gel implants placed retro-pectoral
since they look and feel more natural, are more stable, less likely to ripple
or have complications needing revision.
Implant profile is irrelevant in the retro-pectoral position since the
muscle compresses it. Unfortunately, you
have not provided any photographs but you give a history of two pregnancies so
it is possible that your breast has drooped.
If that is the situation, I recommend a new technique called Breast
Augmentation with Mini Ultimate Breast LiftTM. Using only a circumareola incision it is
possible to reshape your breast tissue creating upper pole fullness, elevate
them higher on the chest wall and more medial to increase your cleavage. Through the same incision, implants can be
placed. Aligning the areola, breast
tissue and implant over the bony prominence of the chest wall maximizes
anterior projection with a minimal size implant. 22% of women who undergo breast augmentation
alone require revision within 2 years because they are dissatisfied with the
result. Best Wishes,Gary Horndeski, M.D. 

Thank you for the questions. Despite your good description of your body type and goals, online consultants will not be of specific enough help to you. Generally speaking, I prefer the use of the sub muscular (dual plane) positioning of breast implants for the vast majority of patients seeking breast augmentation surgery.   I think that the outcomes associated with this positioning tend to be better long-term and associated with fewer downsides. Also, 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. 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 “full 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.
 The use of computer imaging technology may also be very helpful during this 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.
I hope this (and the attached link) help.