K.A.
First, let me congratulate you for continuing to nurse! You are doing a wonderful thing for your child. World Health Organization recommends to breastfeed for *at least* 2 years, longer if mutually desired by mom and child. Forcing weaning at 6 months or a year, which is standard in the US, goes against basic human nature. It is not unheard of for kids in upwards of 7 to be breastfed in countries that practice child led weaning.
To answering your question. What your little one is doing is perfectly normal! She will increase and decrease depending on her needs. Some days she'll barely nurse at all, others she might try to nurse like a newborn. Especially if she's feeling a cold or something coming on or stress etc. As your child gets older they can get milk out faster and more efficiently. It is possible that in a matter of only a couple minutes she's gotten her fill because she was able to get the milk out better than when she was younger.
I nursed all 3 of my children well into toddlerhood. My first child nursed until he was 3, through my pregnancy with my second and for 2 months I nursed both of them. He cut back a lot during my pregnancy because he didn't like the change in milk and getting kicked by his brother. He nursed a number of times after his brother was born and then decided he was good to stop. My second was about 2 months shy of 5 years old. The last time he nursed was a couple days before getting the positive test for my third. I was extremely sick when he asked one day. I asked if I could just cuddle him, he said yes, and that was it, that easy. My third is 3 1/2 now and nursing. Some days she only nurses a couple times, other days she nurses all day. When we get illnesses in the household, she gets over it the fastest and with the least severe symptoms, if she gets it at all. It was the same way with my older children when they were breastfeeding as well.
Do what is right for you and your baby. Ignore all the naysayers. They are wrong!