Hi there, I am aiming to breastfeed, and don't want to buy a steamer steriliser [I live in a tiny flat and funds are restricted], so, I was wondering if I can just use my metal food 'fold out' steamer [ obviously cleaned first] in a pot on the stove? If so, how long would I steam the bottles for and how long would they stay sterilised for if I don't lift the lid off?