Whats happen to ma hair?

well last summer i put this product in my hair and i would wear it all day and when i got home from school i looked in the mirror it looked wavy ish. so about a few weeks later i shaved my head bald okay. so now its been a aniversery and im growin my hair out again. sorry i grew my hair out that last summer and it was wavy when i applied the product. so now its been a year since i grew my hair out alll the way and now when i put the same product on its stays straight all day and all night. i was 14 around that age wen i had long ish hair and it was wavy with the haircreem and now this summer i apply it and its straight with the same product hair creem why is it straight now but then it was wavy. was my hair going throgh a stage or somthin?