Non flowering cherry blossom tree

frenchy999

I have what must be a 30yr/40yr old or more cherry blossom tree. It flowered very well until the year we had the Beast from the East, and then got no blossom that year. I then decided a prune of the dead wood and some leggy branches was long overdue. The following year also had no blossom. I pruned it a bit more to try to get some shape back into it, but was a bit scared of taking too many branches off in case I killed it off, so hard pruned in some places but not others. It hasn't had any blossom since. I am wondering whether I have done more harm than good by not doing a hard prune throughout the whole tree. Do you think a severe prune this year will re invigorate it? If so, about what diameter of branches should I take it back to and when is best for this? This tree has always blossomed later than most others of its type in our area. Thanks.