Unless you are under care of a doctor/therapist, self prescribing estrogen on a daily basis can be bad medicine. Blood clots, liver problems, etc. You might want to rethink that.
But, to answer your question, I recently read a book titled "the man who grew two breasts". It was a collection of real medical mysteries originally published in the 30's. The subject of the story was a 70 year old male who had begun to develop breasts and went to his doctor. In that age group, gynecomastia (moobs) can be the sign of serious illness (lung cancer, pituitary or adrenal gland tumors). After a long period of medical testing, they were at a loss for the origin when the wife inadvertantly discovered the cause--they had sex about once a week and she used a vaginal cream which contained estrogen. The doctor estimated that lthe number of times over the course of a year that they had sex contibuted about 1 gram of estrogen to his system for a year, or .6 mg per every time or about once a week.
So yes, it is possible that one could develop breasts though a weekly application of something like estriol USP, which is a bio-identical estrogen , ( a non-perscription preparation) in the proper amount and which is available in vaginal creams and can be had at places like iherb.
Most research indicates that bio-identical hormones are safer than synthetics like premarin, but one should be very careful when it comes to hormones, and try to find medical guidance.