Aww taz,i've been there,if she's so used to always being with you then she's gonna be terrified when she sees you leave,why dont you try leaving for a minute,maybe popping to the toilet,after that try and progress to maybe popping to the shop then returning,as she sees that you ARE coming back she may start to settle,at the moment apart from your mum she has you 24/7,assure her you WILL be back but that you have to go and get her some sweets or something,i tried that with my youngest when she was little,told her i had to go to the shop and get her sweets then i'd come back,when she saw that i was coming back she started to relax,its tough when you see them upset but its important that she starts mixing now,so she can grow up a happy and content little girl,good luck!