How long will it take to get back to this length?

I had really long hair, about at my bum, I had to get it cut in May ( confirmation, and my mum surprised me by physically forcing me to go after school( she drove me straight to the hairdressers after school) Anyway, Its about midway at my back, and Im super pissed about this. My hair was part of my identity and I feel like its gone. Im really obsessed with trying to get back to how I like it, ( i.e vitamins, Biotin) But i feel so uncomfortable with how short it is, I know I sound super weird, but I dont want to be obsessed about it, I was really happy with the length it was. Anyway, to cut a long story short, 1 How long is it going to take to get to the previous length. 2 Does Biotin work? 3 Do You have any tips or advice, or p experiences, Any advice would be greatly taken