How to get this feeling of rush outta me, I dont want to start a career OLD?

So I want to become an Interior Designer. I am 17 and about to become a Junior in High School. My whole life I have wanted all my goals to be completed in my early twenties. Have job, married with children, and dream house. See I already know that college is MANDATORY because if Interior Design doesnt work out I will have a BA. See I am okay with that but then I will also NEED and WANT to go to a Art & Design college. I have no clue how long you stay there and by the time I am done I am guess I will be like 28. I want to marry after college but Id be so old and I always wanted to have kids young. So once I finish Design school I will have to try to get into a firm. Also my goal now is to enter Design Star after Design college but I am so scared the show wont be around by the time I finish Design college. How can I stop trying to rush growing up and become patient...? Also would it cost a lot to go to college and design school?