I would try either @Promod or @Mango . I found a lot of long shirts at Mango recently, and I recall Promod having long cardigans so if you want to wear any shirt underneath it becomes easier with a basic cardigan on top. Try @Zara for more formal tops if needed. Also if you wear long skirts, Mango usually has the most variety I find. Let me know if that works out for you!