Most of the people on this forum would love to just wake up one day and be their target gender, but unfortunately it isn't that easy, so we all have to make the best of it! I've been round in circles trying to figure out what is going on with me, from "I'll do anything to be a boy" to "Well I can suck it up, I'd rather be an unhappy, yet certain with what's going on, chick than be a potentially still unhappy boy and not know what is/isn't going to happen and when" to "I'm not man enough, I won't be taken seriously, I'm going to be put in a mental institution, etc" to "maybe if I dress and act super manly I'll feel better" (didn't work at all, I was trying to be something even farther from what I feel is ME) finally to my breaking point, where I need to do something, ANYTHING, to feel closer to myself, I may not be 100% male, but anything is an improvement! While before I was scared and ashamed to tell anyone about this, but I've finally told a few people, and I'm going to be getting some help with it soon, so I'm very happy about that! I wish I would have spoke up and asked for help earlier, but I didn't so I'm not going to dwell on the past, but hold out hope for the future! I'm done making excuses for myself, I'm done trying to suck it up and get over it, now is the best time to take action!
Telling someone like a doctor or parent that you're having these feelings and want to talk it through and figure out what's going on, is always a good first step! Just because you're in therapy doesn't mean that once you do that there's no turning back, therapy is designed to help you figure out what you really want and how to go about it! If you end up going to therapy for awhile and then come to a conclusion that you don't want to transition at all, then you don't take it any further! Big deal, no harm done! Everyone's transition is different, there's no right or wrong as long as it's what you feel is best for YOU.
I think a lot of people wait to do anything until they know they want the whole shabang, and tend to dismiss the idea of transition if they don't fit the invisible mold of what a trans guy 'should' be. At least that's the way I was, and just from nosing around the forums, I don't think I'm alone!
Just take everything at your own pace, I would highly recommend therapy as it's the first step and doesn't cause permanent damage by any means, and I'm guessing puberty blockers wouldn't have any irreversible effects (that's just a guess though) so they wouldn't be a bad idea!