New implant rod - no period

So i have had the rod a little over three years now, only last month i got it replaced with a new one. So with the first one i had all sorts of irregularities with my period. It started off as regular getting it at my expected time in the first month. The next month i got it early, and it didnt go away, for 3 whole months! 
I went to the gp who put me on the pill aswell and said to skip the placebos. So i did for a while, and it worked.
But after a while it stopped working. I was getting my period again. But at a regaluar pace. So i stopped taking the pill and everything became normal again. 
I was expecting with my next rod for everything to stay the same. But 1st month in and im already 5 days late for my period. Even though I experienced all the typical PMS symptoms. 
Im wondering if a new implant has higher dosages of the hormone at the beginning and thats why ive missed it this time?