Hi Tammy,
When you say that your mum has noticed that your voice is sounding feminine, do you mean does it sound like you're hitting the high notes? If you try to control your voice by making it sound a little bassier, then perahps she won't notice it as much. The same thing happened iwth me a few months ago, and my mum has more or less grown accustom to the sound of my voice.
Gina