Have you checked your state pension payment for April to confirm you have received your annual increase?
From April 2018 your basic state pension has increased by 3%.
If you are a couple receiving state pension you should now receive £164.35 instead of £159.55.
If you are an individual your increase should be from £122.30 to £125.95.
You have received notification of this increase if you haven't call the Pension Service now!