Hi, schoolgirl. Some out-of-the-box thinking may be in order here. I'm guessing that you have two objectives:
1. a walking friend whose company you enjoy;
2. personal safety.
Who says that your walking friend has to have two legs? You could easily arrange to borrow a friend's dog every day.
Most dogs in America do not get enough exercise -- and not enough human companionship either. A friend's or neighbor's dog would jump at the chance to go on daily walks with you!
Many years ago I borrowed my neighbor's family's Border Collie mix to go on day hikes with me in the Northern Sierras. Gurr (yes that's really his name) loved every minute of it, and I really enjoyed his company.
By the way, it would be best not to choose a gigantic dog who pulls hard on the leash. :)