I am 64 and recently filed for Social Security. I receive 1471 monthly from State Teacher's of Ohio Disability/Retirement until July of 2019 if I am still living. At that time it will drop to 750 $ a month retirement only. I had a couple strokes. I had 25 or 26 years paid in to Soc. Sec. They said I will get 620 # month as I lose about half because of STRS Dis./Ret. and the fact I did not pay into SSec. the last 7 years because I taught part time and then full time .They said that dropped my average from what it showed on their website for my retirement.
I'm sorry to hear about your health problems.
I'm not really sure what your question is, but it sounds like there are 2 separate things working against your Social Security benefit rate. First, Social Security retirement benefits are calculated based on an average of a person's best 35 years of inflation adjusted earnings (https://www.ssa.gov/pubs/EN-05-10070.pdf). So, what the Social Security representative was apparently trying to explain is that, if you only had 25 or 26 years of Social Security covered earnings, 9 or 10 zero earnings years are being averaged into your benefit calculation. Thus, the yearly average and your resulting benefit rate is lower than it would have been if you had continued working in Social Security covered employment for 35 years.
Secondly, if you are receiving a pension based on work that was exempt from Social Security taxes, the Windfall Elimination Provision (WEP) would likely cause your Social Security benefit rate to be reduced even further. For more information on WEP, refer to the following pamphlet: https://www.ssa.gov/pubs/EN-05-10045.pdf.