I've grouped my answers to these two gender identity related questions since they may overlap a bit, FYI
For context, as it said above I'm AFAB non-binary with some experience of dysphoria. Very conflicted over any idea of medical transition.
'Gender envy' isn't a term I'm super familiar with - the internet is telling me something like "feeling jealous of someone else's gender presentation" but please say if that's not what you meant! It sounds a lot like what I can feel sometimes looking at androgynous presentations from male-bodied people (think the legendary David Bowie or Harry Styles in a dress on Vogue) - sometimes I do just feel viscerally upset that they can just put on some lipstick or a skirt and be "trailblazers" and "visibly doing gender****" while whatever I do, people look at my body shape and breasts and go "woman in jeans". It's really frustrating and it can be confusing for me because sometimes I feel like I want a male body, but because then I could be visibly read as non-binary/gender non-conforming, rather than because I actually want to be a guy. That's a bit long but that's basically just my experience - I imagine lots of people will feel it differently and certainly for me it's very tied up with dysphoria, and I could imagine it being a more "euphoric" experience of appreciating someone else's gender.
I can really sympathise with hating breasts so...high five?
It can feel pretty isolating when everyone around you is going on about wanting larger ones and how cool yours are, but society's a ***** and you're not alone.
Other users have spoken very eloquently about how that can be a cis woman thing as well as a trans guy or enby thing, so all I'll do is reiterate that how you feel never means you're forced into a certain identity. If anything, I see my dysphoria as very secondary to the main reason I'm non-binary - which is very simply that I am not, and don't want to be, either a woman or a man, and being this way makes me happy. I'd also really, really echo @sinfonietta's point that you can make all sorts of changed to your appearance and dress to make yourself comfortable without needing a label - that journey can even be an important part of how you get to a label you like. If you do want to bind your breasts please do try and do that safely though
The short answer is: whatever you want it to?
Gender identity can seem like a scary binary choice sometimes, because we do still focus on binary transition models and "coming out" into a fixed gender category, but plenty of people can feel like their gender identity fluctuates (look up genderfluid) or that they have no gender at all (look up agender or neutrois). If you just have that feeling of being genderless, acknowledge it, and move on, that can be all you want to do! Equally, on days you feel less 'gendered', you might want to experiment with different dress, pronouns, names or whatever and in that case go for it. It can be tricky explaining to people that you don't always use the same name or pronoun set and it might be helpful to actually have some fairly in depth chats with supportive close friends about how you're going to play it and how you can let them know what you're comfortable with at any given time (pronoun badges, style of dress, asking etc)
You also don't have to drop 'lesbian' because you're not always a woman or aren't at all a woman - you use what's right for you and what you feel comfortable using. Equally if 'lesbian' doesn't fit right anymore, there will be plenty of other terms like 'queer', 'sapphic', 'gay' etc you might like better.