i'm looking to construct my own bike. i'm a thrillseeking teenager who loves to ride his bike fast but i also need it to be easy to use in a normal slow ride to school every morning. i'm currently 5"7 weighing around 60kg

i'm new to this forum and have never researched bikes before so i dont know any of the biking jargon or brands

the ride each morning is between 10 and 15minutes each way. i also often go on rides for an hour along the river on road with my friend who uses a racing bike. i'm looking for something that would be easily usable in this situation aswell. i need the bike to be easy to use for going up long and steep hills so a light bike with low gear possibilites would be useful.

any recomendations on parts i should try and purchase? and their approximate cost? my budget is rather low(around 160€ a month) and so i'm looking to build this over time by saving up.

i would like it to have:

light frame(carbon is out of my price range??)
front and middle shocks
brake disks
trigger gear system(not rapid fire)
21 or 27 speed gears

i already have continental treaded tyres and an old set of road tyres on my current bike that i can easily transfer if the rim size is the same. running on a 26inch rim i believe