To solve this question we have to make deduct these 2 years. 2100 minus 1991 will give the answer.
You are 109 years old.
(1308 months are passed.)
From 1991 to 2100 there are 109 years. If you want to learn your age in 2100 (born in 1991) your age is 109.
Let's see what will be your age if you born +1 or -1 from that date.