Ok so my freshman year gpa was bad 3.14 uw because i had family problems and this year everything is good and i have a 3.8-4.0 uw. Therefore i can not do nhs until senior year. Do you guys think its even worth it to join? I want to apply to competitive colleges and idk if i should join or if i shouldnt.
The only ones that will care about NHS are you, and maybe your parents. For colleges, it will carry as much weight as your perfect attendance certificate. 
^
NHS is a redundant award in terms of college admission–you get in to NHS if your grades are high enough, but your grades are already being evaluated anyway. It is a nice thing to have in the yearbook, and you get to wear an extra stole or cord at graduation.
NHS isn’t worth that much, especially since you won’t have a leadership role. No point joining in senior year.