It says Ynys Felen not felin.
Go on google - Calvanistic Methodist Births/
Baptisms Anglesey ( pre 1837 ) and under Margaret Williams you will find her father & mothers names and birthplaces.
I am not sure where ynys Felen is whether it is in Trewlachmai or Llangwyllog, but maybe on 1841 census they are still at that address.
All the best, Gwynneth