Bone Density: An important factor to consider
In general, the maintenance of healthy bone density in all people is partly dependent on both estrogen and testosterone levels. When an individual's body produces estrogen as its main sex hormone (as in the case of female-bodied people), that estrogen in healthy levels protects against bone loss. If a female-bodied person were to begin testosterone therapy, there would be a time of transition in the body while hormone levels adjust. While testosterone would soon become a more dominant presence in the body of a trans man, he would still retain some estrogen in his system, both through the presence of his ovaries (if he has not had an oophorectomy) and/or via the natural aromatization of testosterone into estrogen (which takes place whether or not the ovaries are still present and functional).
Testosterone, like many anabolic steroids, was classified as a controlled substance in 1991. Testosterone is administered parenterally in normal and delayed-release (depot) forms. In September 1995, the FDA approved testosterone transdermal patches (Androderm), and many transdermal forms and brands are now available including implants, gels, and topical solutions. A testosterone buccal system, Striant, was FDA-approved in July 2003; Striant is a mucoadhesive product that adheres to the buccal mucosa and provides a controlled and sustained release of testosterone. In May 2014, the FDA approved an intranasal gel formulation of testosterone (Natesto). A transdermal patch (Intrinsa) for hormone replacement in women is under investigation; the daily dosages used in women are much lower than for products used in males. The FDA refused approval for Intrinsa in 2004 stating that more data regarding safety, especially in relation to cardiovascular and breast health, were required.
I think this approach is fine. I must say having been doing this for years, treating hundreds and thousands of men I have been underwhelmed with the results with topicals. Injections can cause peaks and valley and I have many younger men inject twice a week that smooths out the peaks and valleys. I think it is appropriate to follow the advice of your primary doctor and endocrinologist. I have just seen too many men spend months or years with gels with sub optimal results. Many men are diagnosed with depression and are not really depressed (I have no idea if this applies to you), but the presumed depression is base dupon low T.
My recommendation would be to pursue this but if a few months pass and results are modest consider another approach. Pellets are one approach to have smooth levels of T and are placed every 4 months.