Alright, listen.
I understand you're considering starting HRT, and that's a big decision, so it's only natural you have fears and doubts. It's also natural to seek advice and confirmation from people who have already been through this process.
You ask what it was like when we decided to do it. I believe you want to know what it feels like -- what is the feeling we had when we were certain, when we knew for sure that this is what we wanted. Well, allow me tell you.
That feeling doesn't exist.
I also had doubts when I started. But I started anyway, because, given what I knew at the time, I believed it was the right choice. Now I can tell you that starting HRT is the best thing I've ever done -- but this is something I can only tell you in hindsight.
Your post is very similar to several ones I have seen from questioning people asking what it feels like to know you're trans, or what was the moment when you figured it out. They seem to believe they can't act on their feelings until they're 100% sure. They seem to believe there is a magic moment when all doubts disappear. Well, there isn't.
Mind you, I'm not telling you to start right away either -- it's perfectly fine to take your time and think it through. Hell, I'm not even telling you to start at all. You're the only one who can tell if this is right for you. It's a frustrating answer, I know, but it's the only honest one I can give you.
I hope this doesn't come across as rude, but I'm honestly tired of seeing trans people riddled with imposter syndrome, second-guessing every step they take, and holding themselves to an unrealistic standard of being absolutely certain of everything. You will always have doubts. Don't let them paralyze you.