In the 1960's, medical care wasn't available for me and I knew it. I would have to wait until the mid 1970's and even then it was difficult to locate treatment. My only tool for dealing with dysphoria was distraction. Keeping busy and working on something I found very interesting. That worked somewhat during the day but in the evening when exhaustion was setting in, distraction was difficult so I would feel the dysphoria more.
As for waiting until the school year is over, that is your decision however the first few months of treatment very little will happen toward a transition. Even if you were permitted to start HRT, it could take close to 6 months at best before much becomes noticeable. Another issue is it takes a while to accumulate a new wardrobe and become comfortable wearing it. You might need the better part of your summer break to work on your feminine image.
I feel coming out to your parents would be a good first step though coming out at school at this point isn't a requirement.