But you are not missing out.
Yes you do not have a full state pension, but your NHS pension will pay an amount to 'top up' so you will receive the same amount of money.
The full state pension is £203.85 you would receive that if you had never paid into the NHS pension.
But you did pay into the NHS scheme and were contracted out.
Lets say the NHS pension is £100 pw.
So if you had not paid into the NHS scheme you would get £203.85 a week.
Lets say that was reduced by £15 a week so you get £188.85 state pension.
That means you get COPE, so your NHS pension is £100 pw + COPE of £15.
So you receive £115 from the NHS.
So if you had not been contracted out and still payed into the NHS scheme you would get £203.85 + £100 = £303.85
Contracted out means you get £188.85 +£115 =£303.85.