How much time passes in Philip Pullman's His Dark Materials trilogy.?

I am having a hard time figuring out the time progression from the beginning of the first book to the end of the third. Does it span weeks? Months?How much time passes in Philip Pullman's His Dark Materials trilogy.?
2 years pass between the first and the third book, Lyra is 11 from my memory at the start. Then, in the last book, she finally reaches maturity/teenage at the age of 13.How much time passes in Philip Pullman's His Dark Materials trilogy.?
I'd say at least a year. Think of all the time spent travelling, in the first book especially. And it's enough time for Lyra to mature from a little girl to a woman.