Regular monthly period with nexplanon

First 2 years i bled every 3 months and now coming up on the 3rd year I’m gettin regular monthly periods 25 day apart ! It’s been like clock work being able to predict what day my period will be on and for the first time I actually got it ! Should I be worried ? The birth control is suppose to be irregular bleeding . Iv never heard anything about Regular bleeding with this birth-control . What if it’s not as effective anymore? Should I see my doctor ?