Lady Elizabeth 'Isabel' Stewart - Had children at 2 and 15

Lady Elizabeth 'Isabel' Stewart had 2 children between the ages of 2 and 15 years old.
Tip: Correct the birth date of Lady Elizabeth 'Isabel' Stewart (born circa 1517) or the following children:
Janet Sutherland, Alexander Sutherland

Janet's birthdate is fine I think but Alexander was born when Elizabeth was 2 according to the current dates.