Hi Carmen, and welcome!
I'd advise you to start talking to your wife as soon as possible: ask her how she's feeling; tell her you've noticed she's been a bit off lately; ask if there's anything wrong. Then if appropriate, tell her what's been on your mind; how serious it's been getting; and what you intend to do about it. Be honest and open, and hope for the best. You never know: she might simply be tired & stressed with juggling her responsibilities. Or it could be that she's noticed how unhappy you are and is worried about your future together. Until you two start talking, you have no way of knowing for sure what's going to happen.
It's encouraging that your wife has previously said she'd support you, but as Dena rightly said people do change and the addition of a child could have changed the way she views things. You said that it seems something changed a short time ago: well, how old is your daughter? Could it be that your wife has become accustomed to living up to society's expectations, i.e. presenting as a stereotypical married heterosexual couple with a child? There's quite a bit of social prestige that comes with that ring & the baby, and you may find she's grown to like it and that she doesn't want her new-found status to be threatened by your marriage becoming more non-traditional. Personally, I sincerely wish I'd transitioned when I was your age, and I regret having wasted too many years whilst struggling with dysphoria in an inappropriate marriage. My coming out marked the end of my marriage but I'm much better off without him.
As for your daughter... I have two of them myself, and I strongly urge you to come out & transition sooner rather than later, if that's your intention. Young children can adjust very well to a parent's transition, but teenagers (including mine) and adults can find it much more difficult to adjust. And plenty of kids are raised successfully in single-sex parent households, including households where a parent has transitioned. Being trans is nothing to be ashamed of, and it isn't harmful to your child. You'll be an even better parent to her once you're happy within your own skin.
One final point: gender dysphoria doesn't get better on its own. If you need to transition but decide to suppress it, it will get stronger over time until it eventually becomes unbearable (as you've noticed over the past 5 years). You do have the option of choosing to go back into the closet in an attempt to save your marriage and make things as stable as possible for your daughter, but take it from someone who's been there: you'll be setting yourself up for many years of pain and torment if you leave your dysphoria untreated. You've already felt it getting worse over 5 years: imagine what it feels like after another 10 years? Or 15? Or 20? And how much more difficult will it be to come out again and transition after all those years have passed? No, if you need to transition, you're much better off ripping off that Band-Aid and doing what you need to do as soon as humanly possible. It's kinder for everyone.
