Sims aging differently

I have found an aging problem with my game; My Sims lifespans have changed and I was wondering if there was a way to fix this issue?
I have my Sims on normal lifespan and some of the days are different for example: my toddlers sometimes age from 7 days and sometimes they age from 9 days.
This problem is not just happening to the toddlers but to all my Sims. The children and teenagers are between 13-14 days and my young adult/adult Sims are between 22-24 days. This has become a problem as younger siblings catch up with older ones. 
I don't use any CC content and this started when I installed seasons which was when the game came out.