What can I do for stretched, loose skin on upper breast? I'm 5’ 7” 150lbs and a natural 34D. (photo)

You need a formal evaluation by a licensed plastic surgeon and expert in breast augmentations to determine what is best for you and your goals.Proper breast enlargement is not a "cookie-cutter" procedure where the same technique is applied to every patient. Every woman who comes to my practice has unique needs and different goals for her breast augmentation. As a board-certified plastic surgeon, I always listen carefully to each woman's concerns and thoroughly discuss the key points of the procedure. For those women who prefer a "Natural Breast Augmentation" without implants, fat grafting is a safe, natural, and minimally invasive approach that offers low-maintenance, long-term improvement in size and contour. After harvesting the fat from your body, we purify and enrich the fat before injecting it in the desired areas to improve volume and shape.
My experience performing thousands of aesthetic breast surgeries in a wide anatomical range of patients enables me to achieve consistently beautiful and natural results that are customized to each patient’s body type and goals. These results are the product of extensive communication, meticulous planning, and skillfully executed surgery.
I suggest consulting with a board-certified plastic surgeon and expert in Breast Augmentation surgeries. - Dr. Cohen

Adding volume to the breasts (augmentation) and tightening the breast skin with a breast lift are two ways that can used to tighten the skin. Augmentation will enlarge the breast and a breast lift will require scarring that might not be acceptable. Nonsurgical methods that are available include use of ultrasound , radiofrequecy, and use of light or laser processes. These all act by generating heat which causes skin tightening. The results are variable , typically require more than one treatment, and may last up to several years. Consult a breast surgeon who has these modalities available to determine if you are a good candidate.

Patient concerns regarding the appearance of their breasts can typically be divided in two pools: volume, ptosis (droop). The procedures to address these issues are as different as the issues themselves. However, these concerns are not mutually exclusive (some want smaller less droopy breasts and others want larger less droopy breasts).
There are two factors which can help to answer the question of which surgery will deliver the most satisfying result: mastopexy, augmentation or both. Patients must first consider the position of the NAC (nipple areolar complex i.e. the pigmented portion of the breast) as it relates to the inframammary crease. If the nipples are at or below the level of the crease the patient may benefit from a lift or mastopexy. The breast lift is designed to elevate sagging breasts to a more youthful position. It also helps to reshape and tighten the skin of the breasts. This is typically accomplished via a periareolar (around the nipple) incision with or without a vertical incision.
With reagrds to your specific question, patients who are content with their size but are seeking to address laxity or ptosis (excess or loose skin) are candidates for mastopexy. This can often be performed with limited volume loss (depending on the degree of droop). While this will not directly address stretch marks/striae of the upper pole, it will re-suspend the breast, correct for sagging and address lower pole laxity. Alternatively, RF BodyTite is a minimally invasive approach to breast ptosis by tightening (via heating) the upper pole skin. This is a newer (and less reliable) technique which shows promise and may allow for a lower scar burden. It will also directly address the skin at issue in your question.Satisfaction is often a function of establishing a clear understanding of goals and management of expectations. Duration of result will vary with the individual (and is subject to both time and patient specific changes).
There is a procedure for every problem. To determine which technique is right for you, consult with a board certified plastic surgeon (ABPS). Patients should discuss their concerns with their physicians in order to make an educated decision.
Donovan Rosas MD
Board Certified by the American Board of Plastic Surgery
Member: American Society for Aesthetic Plastic Surgery, American Society of Plastic Surgeons
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It is hard to make much of an evaluation from your photographs, but from your explanation, it seems there is nothing to do to address this looseness.

It appears from your photos that what is concerning you is stretch marks.  Unfortunately they are hard to treat.  I encourage you to take good care of your skin by keeping the area well moisturized and use sunscreen with any sun exposure.