Not sure where you are located, but it definitely sounds like they are not up-to-date on the most recent studies. If you've already gone through puberty, it is my understanding that the hormone blockers are moot IF you are on T. The reason trans guys only take T and not E-blockers is because the T does everything necessary, whereas MtFs take E and the T-blocker. It sounds like they may be taking the overly-cautious route. If you are in a well-populated area, look for other doctors who are not so conservative* with their treatment style. If they are the only options for doctors in year vicinity, you can try printing off the recent studies (such as the one mentioned in the article at
http://www.advocate.com/politics/transgender/2015/02/01/study-transgender-kids-are-not-confused-about-their-gender-identitie ) to have them read. The treatment standards for trans kids AND adults have changed a LOT in recent years. Sometimes, doctor's aren't up-to-date on their research and they need prompting. Sometimes, just demonstrating that you are really competent and knowledgeable in the area is enough to prove to doctors that you are serious. Sad that we have to prove our seriousness, yes... but it's turned around treatment plans for me when doctors were initially resistant.
Good luck! Never stop being your own advocate!
*I really do mean conservative in their treatment style -
not a comment on their politics!