Safety is all relative.
But SE Asia, and Asia as a whole is very safe IMO, male or female. This should be least of your worries.
Most the popular places a tourist would go, and the backpacker trail, is like minded travelers and will be easy to hang out or travel with a new companion as well.
I only travel solo until I got married, and my wife also travelled solo before I met her, she is a petite Chinese and had traveled all of Asia and EU before I met her...
Relax..you will have a fine time...
Adventure Travel to Colombia, Costa Rica, Nicaragua, Honduras, Guatemala, Mexico, Thailand, Burma, Laos, Cambodia, Vietnam, China, South Africa, Morocco, Turkey, EU, USA National Parks, enjoying culture, cuisine, motorcycling, scuba diving, surfing, sailing, rafting, hiking, fishing, camping, nature, wildlife. Get a Guidebook, and get lost!