Taking care of one's sister in Madinah Munawwarah without performing Umrah

I came to Madinah to my sister who went through a big hardship. She is emotionally in need of me, she can look after herself now physically after recovering Alhumdillah. I did not come with the intention of performing umrah and wish to spend all available time to help my sister (I believe this is also ibaadat).

Will it be a sin on me if I do not perform umrah before leaving? I have never visited Makkah before. I am mentally extremely worried for my sister. I had always wished and prayed for visiting the Ka'aba but I don't want it to be a half-hearted visit.