Male bettas build the nest and tend the eggs. You should be proud of yourself! Males only nest-build when they are content, healthy and in a good environment. The biggest bubble nest I ever saw was nearly 6 inches across.
And no female is necessary. The bubble nest is mainly just a sign that your fish is in prime health and happy. You could introduce a female if you want, but breeding bettas is a bit more complex than breeding other fish. You also have to prime the female to get her in "the mood", otherwise, she will fight and potentially kill the male instead of mate. There are a lot of websites that have info. I've bred bettas before, and it is very interesting if you decide to try it.