I'm looking for recommendations for full length black leggings to wear for the school run the heading straight to strength training at the gym. I'd like them to be very opaque and to not fall down. I'm a 16 so at the top size for many exercise clothing brands. I'm happy to pay a bit more for really soft good quality leggings but also more than happy for cheaper recommendations. Have toyed with Sweaty Betty, Lululemon and My Protein but all get mixed reviews. Anyone got any great suggestions?