When am I safe from head lice?

I found out yesterday that I had head lice, and the day before that I found out that my sister had it, and I got it from her because she's been sleeping in my bed with me. She had three life in her hair and eggs and yesterday after combing through my head with a lice comb, I only found one louse and a few eggs. We washed everything and I boil the comb and my hair ties after everytime I use them. My mom bought me some lice stuff that I spray in my hair and let it sit and it's supposed to kill all of them. I put it in my hair three times now and slept with it in twice, and I combed through my hair three times now and I don't see anything. Am I lice free now? As in, can i let my hair down and can i lean back on furniture? The stuff my mom bought got five stars and everyone said after one use all of the lice were gone. My head felt itchy last night so I was worried I still had some. Thank you! I hope I provided enough information!