I'm 14, I started hunting last year although I was alone, this year I was with someone. I'm not sure if a muzzle loader is the right gun for me because I only get one shot and i'm not that experienced. I've only shot a deer with a muzzle loader, this year i've shot 3 times in the field got 3 deer.
You only need one shot. Also, you have already proven you only need one shot. Do you want to stick with a muzzle loader? It's your choice.
black powder hunting is a lot of fun, although you have to work at closing the distance for the best shot. Modern rifle, handgun, archery, all offer different aspects of hunting. If you enjoy black powder hunting, stick with it, but don't limit yourself to just that. Try other types of hunting, then you can decide which one(s) you enjoy and can stay with those. I try to hit at least two seasons each year, sometimes it's black powder/archery, sometimes it's handgun/modern rifle or any combination I can manage. shoot safe
The first gun I got my son when he was 13 was 50 cal. flintlock. My reason was this- I wanted him to know the basics of fire arms. where they came from, the mindset, and frankly, if you can hit with a flintlock consistently ,you ca n shoot any gun because you have to hold very steady all the way through the shot. After he became proficient with that I gave him my 1895 CB marlin in 45-70 with the stock I'd made for it with the cresent butt plate, it looks very original except for the bolt on his 18th birth day........So if you like your gun and your good with it why change?
A newer muzzle loader is just as reliable as a rifle at short distances, if you have the possibility of shooting 300 yards a rifle would be the way to go, also if you don't have the money to spare for a rifle stick with the muzzle loader. a 30-30 is a great rifle if you are not shooting long distances and you can find one fairly cheap. I own rifles and i still hunt with my muzzle loader in rifle season.
A single shot gun of any kind is the best for a beginning deer hunter. As you have demonstrated, using a single shot helps ensure success. You wait for the right shot when you know you only have one chance, and you've proven that by taking 3 deer with 3 shoots. You should be proud of yourself. I would say with this kind of success, you shouldn't have any problem moving to modern firearms. In fact, using a bolt action gun is easier than using a muzzle loader, and with a scope on something like a .243, you can easily double the effective range you had with a black powder gun.