It's most accurate to say she was sent to Paris to live with Jefferson when she was 14 and lived with him there for 2 years before returning to Monticello with Jefferson. I don't find myself inclined to search Jefferson's private papers for details, although the evidence suggest he took pains to keep the relationship secret. The children she bore were later in life, but as you said, she had no agency throughout her relationship with him. Thanks for the comment!