Looking at the records on
https://www.scotlandspeople.gov.uk, which you can search free, low cost pay to view. I can only see one marriage in the County in the period.
JOHN ROBERTSON JANET MCLAREN 25/11/1753 Kenmore
However the children’s names you mention do not always tie in?
Dates are more likely baptisms; also places and Janet’s name vary.
I cannot find records for James, Mary & David that match your post.
ROBERTSON PATRICK JOHN ROBERTSON/JANET MC LAREN 23/09/1756 Kenmore
ROBERTSON ELIZABETH JOHN ROBERTSON/JANET MCFARLANE 22/10/1759 Weem
MARJORY ROBERTSON JOHN ROBERTSON/JANET MCLAREN 17/02/1761 Little Dunkeld
ROBERTSON ANN JOHN ROBERTSON/JANET MCPHARLANE 16/05/1763 Little Dunkeld
ROBERTSON JOHN JOHN ROBERTSON/JANET MCLACHLEN 21/10/1764 Little Dunkeld
ROBERTSON DUNCAN JOHN ROBERTSON/JANET MCLERAN 05/06/1768 Killin
ROBERTSON KATHARINE JOHN ROBERTSON/JANET MCLAREN 24/05/1770 Killin
Colin