Hi Helle
Nature has fed the soil underneath trees since time immemorial with leaves, plain and simple, so I would find it surprising if adding leaves (over a three year period?) was causing a problem of excess phosphorous. I suppose the caveat is the amount you are putting on, but my guess is that you would have to put on an excessive amount (whatever that means!) for leaves to have a detrimental effect. Another caveat is that it is suggested that the leaves of some tree species, such as eucalyptus, should be used sparingly.
Is your veg showing signs of phosphorous excess, such as stunting of peas, or do you have veg which takes first prize at the county show? As Charles says it is better to use your produce as a guide rather than changing your inputs on the basis of a soil test.
Of course, like everyone else who writes on the forum, I am the leading expert in this field so you may need to take my comments with a healthy dressing of sodium – not too much mind you.
It would be useful to have Charles’ opinion on the use of leaves.
John