Voice Change Software use

I'm Currently doing a project requires a female voice but since a long term project and required same voice. I will need to change my male voice to female with software, website or Etc. I've tried many voice changer but they don't sound realistic. Maybe I'm not doing the right setting. I can't afford some heavy luxury gear for it. All I have is a laptop with a newly bought microphone. And a iPhone. If you have any advice or experience in voice change software or changing voice from male to female. I hope you can help me. Thank you very much.