That's how I read it, she has twisted the facts to make it seem like a plausible story but has actually made more problems for herself.
There are a couple of key reasons that point to a possible innocence. First a real lack of motive for murder and second her actions after the fact pointing to a panicked cover up rather than a planned murder.
However, in trying to make herself look better, she has inserted more doubt into her story and increased the possibility of guilt.
For instance, I think it's extremely likely that she knew she was including foraged mushrooms in the meal. Not only did she lie about this at the time for whatever reason, she has now concocted an unlikely version where she didn't realise until days later that she might have included them. This is an obvious attempt to account for her initial lies at the time.
This is hard to believe IMO, and simply increases the question of foul play. If she'd simply owned up to having included them and not knowing what they were, it would ironically be better for her.