letter from Chicago

please check the following texxt/ correct mistakes:

Hi,

I have left hospital today and I’m back in my rented room in Shorewood near Chicago.

I’m very happy.

Martha is coming to Poland on 18.04. We are going to have a good time in The Old Town in Warsaw. She will visit my old place, too.

On 04.02. my sister gave birth to their second child, the daugter and it was John’s idea (Katty’s husband) to give her the name: Ola.

The older child, the daughter Sophia has come down with pox, now.

What’s new/about you?

Take care,

Susan

thank you very much…

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.