My assignment was simple: prove that a triangle whose base angles are the same is an isosceles. But then I found out I cannot use the base angle theorem.

Now I found out that I have included unecessary info or else left out a step, my instructor didn't say for sure.

Does any one have any ideas on an easy way to fix my proof/diagram? Or do you think I should just start over trying to prove it from a different way.

My diagram and proof are attached.

Thank you!