Okay this may be a dumb question but after reading some post I have to ask…. Do you always have to sterilize your pump? I did it when my DD was young but she’s 11 months old now. I sterilize every week or so I only use it about once a day.. If I get a chance just to have a back up. I have the Medela Swing. I clean it with hot water and soap and rinse it out but do I need to sterilize every time??