I started flossing my teeth and found out that my small gap between my incisors become more obvious. What should I do? Do I have to wear braces?

No. The space between your teeth was probably filled with dental plaque and calculus and when you removed it, the space became more apparent. Either that or it was there already and you just noticed it. Not all spaces between teeth need to be closed. Do you "have" to wear braces?, no. If you are unhappy with the space, see a dentist to discuss your options- ortho? Bonding? Other?
Invisalign . Find a dentist who does invisalign - probably much better for you than braces.
Braces or veneers. If those where my teeth i would get porcelain veneers, a simple retainer would work if the gap is not to big.
Maybe nothing. No restoration, like veneers last forever, and sometimes the best thing to do is nothing. It depends on the gap size and how much it bothers you.