Q.Saucer Magnolia
15 year old, zone 5, N CT, always bloomed copiously in early May until 2 years ago. Last year and this year about 6 blossoms. What can I do to help it form more blossoms? The tree is about 20 feet high, with two main trunks and one minor. The tree seems healthy, beautiful green leaves will form in another 2-3 weeks. It seems fine, other than the lack of blossoms.

I would suggest a soil test is a good place to start.
The last paragraph in the article below has information on the necessary soil nutrients and ph information to ensure blooming.
https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-blooming-problems.htm
Here is a link to locate your closest County Extension Office that can help you with a soil test.