What type of braces do I need and how long will it take?

Hello, thank you for seeing to my question and taking time to read and answer it. I am currently 16 years old and when I was 12 I had the traditional metal braces fitted on my upper teeth and I was told they stuck out because did not match my jaw size. I was never fitted bottom braces braces which I thought was weird as I heard that braces is needed on both upper and bottom teeth as they move all the teeth in the mouth. Anyway I attended appointments but after 18 months I stopped attending as I had other issues with my health. I had them removed and was told I couldn't continue the treatment due to not attending appointments (it was provided by the NHS in the UK). My teeth were straightened however I was left with a gap in between all my upper teeth apart from the molars. I am now seeking private treatment and I am wondering what would be the best and fastest type of treatment as I don't really want to spend another 24 months wearing braces. I know it is hard to know without a consultation but anything would be great, thank you!