6 month old kitten howling in the middle of the night! help!?

I have rescued little Sookie from this boy who was tossing her around like a rag doll when she was only 3 weeks old. She has been very independent and obedient at a very young age, every one adores her! She is now 6 months old and because of my neighbor getting renovations done, I have stopped letting her out. My vet has also instructed me to not let her out because she has the indoor vaccine done. I rather she stay inside than play in the sand at the renovation site, she gets really dirty and the dust she brings home. 3 days of being stuck at home, now in the middle of the night she howls for hours! I have only owned male cats and none of them ever did this. Sookie sleeps with me every night but it's becoming unbearable since she is waking me up every hour. At this moment it's 6am and only now she is at my feet asleep because I kept going "sookie shh!".. She hasn't been spayed yet, she is due for a booster shot next week, and her vet has said after the vaccine we'll give it a month and arrange for the operation. Is she mad at me for grounding her? Or is she in heat? Help please! She's "talking" way too much now days. Big thanks! Xoxo