Getting Rid of Relaxed Hair :(

um okay so the thing is, im 16 year old guy and i had curly afro hair they were long and kind of huge so i got them relaxed a week back and after relaxing i found out that straight long hair dont suit on me and i want to get back, so i got a short haircut which is spikes, the sides are short and the hair in the middle are normal, like not too short and not too long.. maybe two - three inches... now im worried how long will it take for my curly hair to grow and when they do grow how will i get rid of em? because i got my relaxed hair cut just after a week because i didn't like it at all and there was no new growth at that time, still there isn't. so yeah how will i need to cut my hair when new grows? like sides are short and i can know that new hair over sides wont look bad but in the middle they'll poof out with straight and it'll look bad no? will it be easy to get rid of straight hair then and maintain curly hair? please tell :c