I think this is a balancing act many of us find ourselves in when we have a SOwe're trying to keep as we transition. They have a timeline in their heads and it's usually a lot longer than ours. Simply put, we've been dealing with this all our lives and feel like a shaken-up bottle of champagne. When we let that cork out, we just want to let everything flow. For our SO's, obviously they're just trying to come to terms with it all at once and need time to process. For many, I think there is a natural tendency to want to slow things down so they can do that. It ends up being a difficult and repeated negotiation as both sides find out new information that affects the timeline.
For me, I totally understand how you're feeling. When I first came out as genderfluid to my wife, she was also talking on the order of years before I'd be going out in public in any real feminine presentation. We've been talking about moving at the point our last kid starts high school and she wanted me to wait until then. That is over 2 years away and all I could think was no way am I waiting that long.
For us, I've tried to temper my exploration of gender presentation to give her time. She's still not seen me wear anything more feminine than stud earrings (not feminine at all when you consider guys wear them all the time). At the same time, she understands that while I currently identify as genderfluid, I still need to explore to make sure I truly understand what my identity is. So getting out in public presenting as fully female is important. So right now I do that in certain safe situations and I have to do it by getting dressed/made-up and slipping out of the house without her seeing (even though she knows I'm going) and then slipping back in and getting it all off before she sees me. Thankfully our house is designed in a way that makes this pretty easy to do, but still.
Sorry, I know I've kinda blathered on here a bit and I'm not sure if any of that was helpful. In the end you have to be honest with her that the timeline she's proposing doesn't work for you. It does no one any good to wait 2 years if the GD is going to be so heavy on you that you'll split or do something worse before you make it those 2 years. At the same time, since you seem to want to stay in your marriage, you'll have to listen to and seriously consider her perspective and try to find a middle ground you both can be reasonably comfortable with.