I find its pretty common for people to be confused about a change in sexuality name when they transition, sometimes you get so used to the labels that describe you that its weird hearing a new one. All sexuality is the relationship between who you are as a gender and who you like. I urged some people I knew to not overthink it, you love who you love and that's that, whether youre a girl or a guy who likes girls or guys. If anyone asks you can always simply say "I like girls".
As for risking any more social distress coming out as trans, that's up to you to decide. Im wondering if it'll make much of a difference if people already know you as lesbian, I imagine most people who arent homophobic tend to not be transphobic either, or if they are I dont know if they see that as any worse than what being a lesbian already is. It's up to you, you can wait until it feels safe to come out or work up the courage to do so, that's your call.
If you are a man and you know all the signs are there its safe to say at least to yourself you know who you are. It gets a little more difficult from here so I wish you luck in your steps to transition if you choose to do so