Although you don't want to know any alternatives, others will read my reply. To them I will say that 'Had she not left....' sounds much better to me for a statement. Putting "not" and "left" together sounds much more grammatical in that sentence..
Although 'Had she not' can sometimes be used in questions, it very suitable for statements. I much prefer it over MMK2210's choice for his (statement)(non-question).