Hi there,
I think the other poster nailed it right on the head--that you are likely an introvert, while your daughter is extroverted. I am introverted, so I can sort of feel your pain, with the demands on your time and the constant "needs" that children present.
I would be organized and plan ahead on how you will spend your days. Involve your daughter in the planning. Maybe the second Saturday of the month is the day she can have a friend sleepover. Maybe on Tuesday evenings, she needs to play independently, but on Wednesdays you and her play a board game. Write it all on the family calendar, where she can see it and she knows what is coming. If she knows ahead of time when she can have sleepovers and your undivided attention, she may not seem so needy.
I agree with the other poster--get her doing some household chores if she isn't already. An 8 year old can do a lot, with a little supervision. If you sort the laundry, maybe she can actually load the washer and the dryer. She sounds like a bright, energetic girl. If you show her a few times how to measure the detergent and what settings to use, she might be a huge help to you! She can also be brought into some simple meal prep, weeding the garden, or dusting.
You can also channel her energy into some inexpensive activities, like a hobby she can get hooked on. Might she enjoy knitting or crocheting, or some simple sewing? Community Ed and even your library might have classes this summer. She could grow her own small container garden this summer. A lot of herbs (like mint) practically grow themselves and are pretty foolproof. She could start today by reading books on growing herbs, and maybe doing some chores to earn money to buy the seedlings and pots. I got my herb garden started last year for around $15, and it sits on my windowsill all year round. Another thought is if you have a nursing home nearby, she could start visiting. Many people do not get regular visitors for whatever reason, and would cherish a child's good nature and smile. Most nursing homes have simple activities where a visitor might be welcome (bingo night). Good luck!