That will require reconstruction with your own tissue. Since you have a had a tummy tuck the inner thigh tissue in the form of a TUG or PAP, SGAP from the buttock or an LD flap are all options. Fat grafting can be added as well later.
Skin sparing mastectomy and radiation
The gold standard in these cases where you have radiotherapy change is autologous tissue using either lat dorsi plus fat grafting or a double TUG flap
implants always have issues with capsules in irradiated breasts
Is that an implant or do you still have the tissue expander? The skin color change is from the radiation. An exam in person will help. Often an exchange to an implant and lowering the fold a bit will allow for a better position. A lift can be done at the same time. Fat can be injected to the skin to improve the texture at some point. An LD flap is often an option if needed.
Breast reconstruction and radiotherapy
Radiotherapy makes the skin envelope tight and natural ptosis is difficult to achieve. Latissimus dorsi flap and contralateral breast lift is good option as you are not able to receive DIEP flap reconstruction due to previous tummy tuck. Several fat grafting sessions is also a nice alternative.
I had a skin saving mastectomy & rads in Aug 2015. I'm worried it is too high and will have a bulge near my collarbone.
Best to seek more second opinions in person! I might suggest doing right full breast lift to see the amount of elevation symmetry attainable. Also might start lipo with fat grafting to left reconstructed breast. Than after 3 months do additional surgery to improve results..
Post op radiation and breast implants
Thank you for your question. Implants are never very good in an irradiated field. If you have had a TT then the next best option to create a more natural look and feel in your breast would be a SGAP flap. The upper buttock lower back tissue is great and available in even the this thinnest of patients. The only issue is that only a select group of surgeons are willing to do this surgery. Ask you surgeon about it and if need be get another opinion. It is a great flap that I frequently use in patients who have previously had a tummy tuck. Good luck, let me know if I can help.