Breeding is an epic headache. I figured I could weigh in. I have bred and foaled out a few horses in my time. I have also had a few horses (aka a pasture full of them) that can't find a home. I think its important to consider a few things before breeding. The mare and stallion and then there are facilities, vet bills and yourself. At 17 how do you plan to support the foal? Are you going to go to college? If not, how much do you make at your job? When you factor in feed, grain, board, vet bills and then your rent and groceries. Which means you need to be, most cases, making more then 8 dollars or minimum wage.
The mare and stallion, I think you should breed them only if you think and others think its a good idea. A lot of people think they should breed their horse but not many people agree with that. Its hard to re-home a horse, even well bred horses. I say this as the owner of the offspring of hall of fame sired horses. I know you don't plan to rehome this foal but really that's dicy. You are seventeen and horses can live 25 years or more. Which means you would be in your forties by the time this horse passed away.
I can respect the desire to be there from the ground floor. But what is your horse training experience? You are there on the ground floor any vices this foal has are your fault and your fault alone. Can you prevent those vices? What do you plan do to with the foal? In addition, if you want an untouched horse to monkey with there are mustangs that are yearlings, they are cheaper then a stud fee and if you are a decent trainer or working with one can make nice horses. They also don't have handler baggage. They are also probably just as well bred as your mare is.
Just my opinion.