Hi Shell190 Younger,
If you have paid contributions for nearly 50 years, you can contact the Department for Work and Pensions State Pension helpline and they will advise you how may qualifying tax years you have and how any contracting out period has reduced your State Pension.
They can also advise you on how the State Pension is calculated.
You may have tax years where you have contributed but some tax years may not be full qualifying tax years towards the State Pension.
State Pension helpline:
Enquiries - 0800 731 0469
Open - 8:00am to 6:00pm Monday to Friday, closed bank holidays and weekends
Northern Ireland - 0800 587 0892
If you need to check the amount of qualifying tax years with HMRC you can obtain a statement of National Insurance to view your qualifying tax years that count to the State Pension.
Check your National Insurance record
You can also obtain confirmation of your contracted out period with HMRC by calling the National Insurance helpline on 0300 200 3500.