I just realized shes starting school in a month

My daughter came into my room in the middle of the night and was mad at me because I wasn't sleeping in her bed with her even though I told her I wouldn't be. We argued a minute (shes a sassy 4.5 year old). Then for some reason I realized next month is August and she starts pre school at the end of the month and my heart immediately broke. Now I can't sleep. We've had the shittiest July. She was sick in the beginning of the month and then it got me a week later. This cold lasted about 2 weeks for us both and then her father ended up needing surgery and in the hospital for over a week. So the whole month of July has just gone down the drain. Even though her pre school is only 3 days a week and 3 hours a day its the beginning of the end of my time with her as a stay at home mom and my heart is broken. Ive cried every year since she was a year old knowing that I could never go back to these special care free times of us being together at home. These are the best times of my life right now. Can someone please tell me some positives so I dont feel like its so bad?? My daughter is my world and has been since the day she was born.