Nothing substitutes for a personal evaluation, a review of your medical history/medications and a face to face discussion of your options.
Unfortunately with out a exam of your tissues I can can only comment based solely your photos. However, hopefully you will find them helpful.
The timing of when to perform a mastopexy is entirely dependant on the patients needs, wants and desires. Having a breast augmentation does preclude a a future mastopexy.
Mastopexy following a breast augmentation is often done following:
1. massive weight loss
2. Pregnancy
3. Borderline pre augmentation need for a mastopexy
4. Large implant placement and normal resulting sag (ptosis)
I recommend that you schedule several consultative appointments with Plastic Surgeons who are experienced and Certified by the American Board of Plastic Surgery. In addition ideally a members of the American Society for Aesthetic Plastic Surgery (denoting by membership as having met additional criteria and a focus on Cosmetic Plastic Surgery).