A member account should have 64? activity. I am not sure but it is around 60+ , You only have 28 activity. To gain more activity you need to wait more activity updates. Activity update is every 2 weeks and you will get 14 activity each activity update, 2weeks = 14 activity. You need to wait a month more to get to member.
Not to forget it also depends on when the account was created. There is potential activity that is associated with it when the account was made and only if you posted once in the two week periods at a time.
Just to correct you Jacee; it is 60 activity not 64 activity:
Jr. Member -- activity: 30
Member -- activity: 60
But you first need to get to the next level of rank to junior member and it looks like you are at 24 activity at 54 posts so you need to wait even longer because you did not post in those two week periods to get more activity potential in that initial time frame.