Hi Dymphna,
Welcome to the forum! I hope you find the forum helpful as you progress through your journey. Many people have mentioned similar difficulties as you describe.
I, myself, have never forgotten my traumas. However I was able to compartmentalize the various aspects. So they did not overwhelm me all at once. I am still working in therapy to put together all of the different events, but that can take quite a while, especially when you're also trying to limit the impact of the side effect.
As to your question how there is no definite answer as to how long it will take you to identify what happened to you. There is no way to know that about. It depends on too many variables. For some it depends on how your relationship with the therapist is. For some of us it takes a few/many tries to find the right match. Some PTSDers have it rolling out, and a therapist may need more of a breaker. It depends on how many traumas you experienced and how long the abusive time frame took place.
Just try to be patient with yourself! That's probably my worst skill...
Best of luck on your journey! It is definitely worth it...