How can I make her happy?

First of all, English is not my first language, and I don’t write much in English soo, forgive my mistakes, I’m rusty and I need to remember lots of things.

My sweetheart Nina ( 13 year old, Female Yorkshire) used to live with my parents in their house, there she had loads of space both inside and outdoors, but they are having some issues with the structure and for the next 2 months I will be taking care of her in my small apartment ( I live in the Center area of the capital of my state ), but she seems kinda depressed, she still greets me when I wake up and when I come back home from college, but she is visually more quiet now.

I can’t go for long walks with her, because she has a heart condition ( she needs to take 2 different meds every 12hrs ) , I tried taking her for a early walk today, she couldn’t complete 100m without starting coughing, she appeared to have enjoyed it, but I’m afraid of taking her on more walks during the day would be more than her heart can handle.

Any suggestions for what I can do to improve her QoL and make her happy again?

I added some photos to show how cute she is, last 4 were taken today.