"Please enjoy this short list of women who don’t meet that definition."

The % of humans who are both externally and internally ambiguous is .13%.

.13%. That's 1 in 7,700. Most people in their entire lives will never meet one person that is medically intersexed or otherwise totally ambiguous.

So, yes, it's a trap, but it's not the trap you think it is. There is absolutely nothing wrong with defining "woman" exactly the way you defined it in your 3rd paragraph, because outliers that are so rare do not dispute the sexually dimorphic nature of the human being, just as the fact that the rare baby that is born blind does not mean that "vision" is not one of the five senses.

You said it yourself: Sex is biological, gender isn't. End of discussion. We can define sex as male or female, and gender according to the sense of the individual. Neither is in conflict.