Reluctant to impose my views as I am, still some remarks that I see as appropriate.
I believe the letter (to someone close to you, presumably,) could sound less a statistical account and more informal.
Like, “I feel happy today because I’ve left hospital…
On April 18, Martha’s coming to Poland and we’re going…
I think you didn’t know that on February 4, my sister gave birth to their second child, a girl, and it was John’s (Katty’s husband’s) idea to give her the name Ola.
Their older daughter, Sophia, has currently come down with [small]pox. [It needs a follow-up: I hope she recovers soon\But the doctors say there’s nothing to worry about…]
What’s new in your neck of the woods? [Looking forward to hearing from you soon]”
P.S. Note that 04.02.could be read differently by the British and Americans.