I think you have a valid reason to suspect gender discrimination, yes. But you are still a long way from a lawsuit; there are steps that need to be followed and you do not get to skip any steps.
Has any of this been reported to HR? If not, that is your first step. (For the purists I will add that yes, there are some circumstances under which this step can be skipped, but there are always risks to doing so and in this situation I would not recommend it. It's one thing if it's a small mom and pop organization with 18 employees and the harasser/discriminator is the owner; it's quite another in a large corporation which likely has policies and procedures to follow in the case of illegal treatment). Report it to HR, in person if possible, and give them a reasonable time to take any necessary action. If that stops it, fine. If not, the next step is to file a complaint with the EEOC and/or your state equal rights commission. Only after you have a right to sue letter from one or the other do you get to go to court.
You might want to discuss everything with an employment law attorney before you go forward.
Two things I am tired of typing: 1.) A wrongful termination does not mean that you were fired for something you didn't do; it means that you were fired for a reason prohibited by law. 2.) The above answer, whatever it is, assumes that no legally binding contract or CBA expressly says otherwise. If it does, the terms of the contract apply.