MMA journey

I’m 16, and I know boxing, Muy Thai, Ju Jitsu. I did Ju Jitsu classes mostly when I was little and now I train daily but with no formal classes just at home. So far at my school I’m 9-0! I weigh 120 which is super light, but so far I’ve faced the following One man who is 180, submitted him in five fights sub 30 seconds One man who is 130 who was notably much faster and took longer One guy twice who’s 150, didn’t know much One man who was 200 pounds and tall😭. But if a longer fight but submitted him I come to Reddit for advice. Bell rang but this one tall lanky and fast dude was very fast, and I could take him down cause he kept moving backwards. Any advice on taking down fast people? I seem to do well vs bigger opponents but takes longer vs light and fast ones