struggling with my 16 year old son and my decisions

hello,

so to fully understand my situation i will explain as much as i can,

when i was 14 i met a girl, everything was very platonic, i got brought up in quite a rough neighborhood so things were not ideal, she became pregnant and frightened, the father uped and ran away so i moved in. my parents genuinly didnt care what i was doing at 14 so i had the freedom to do it.

once the baby was born and i held him, it was a love id never knew existed, it was like my whole life made sense, i spent the next 9 years with this clingy little boy on my leg and i loved every minute of it lol our bond became very strong.

problem was, me and his mother were just friends and through the years she would date other guys and if it lasted they would move in and lets face it, noone waants a hanger on while trying to start a family, i also about 21, i met a guy i really liked and kierons mother was in the process of getting married and kieron (my son) liked the guy so i left. i met a guy and moved to fife, ofcource i still kept in contact and stuff still visited when i was home but i coulnt have kieron around my ex, he was extremly abusive after the first year and i couldnt even think of him touching kieron in a aggressive way.

so fast forward to 2018 and i leave my abusive ex and move home, i take kieron on holiday with my family, i hear him crying in the room and investigate, aparently he doesnt want to go home and things have been super rough for him (i had to hold in my anger at the stuff he told me, adults should have helped him in instead of thinking of themselfs!)

i found out social work was coming to get him when we got home. i was not having this and i asked if he wanted to live with me as i had my own 1 bed then, he agreed and since then hes been living with me. social workers cleared it with background checks and said because of his improvement in school and out that they are gonna close his case!

he started calling me dad after a year ( was uncle andie when he was little, growing up as to not confuse him)

so to the present:

hes now 16 with a gf, hes the typical fifa playing,jake bugg listening football teenager.

im still only 31 so im young enough to game with him and such, im not a big football fan but i watch with him everytime its on (i tell him i like it) so we get on okay but i knew how to be a father when he was in nappys bouncing about! now i just dont know how to make decisions!

we still live in the rough area and im not loaded so i struggle to provide everything.

so the decision im struggling with atm is, he has come and asked if he could stay at his gfs on Saturday night, its her birthday and she having a party, her father has never allowed it but now he is and kieron expect me to allow it now, we also agreed that he will finish his training before getting an apprentice but he has now come and said his gfs dad is getting him one.

i feel like if i say no because i know there will be drinking and partying and his gfs dad already offered him a beer when i told him i didnt want him drinking alcohol just yet, that he will hate me and ill be taking away an experience of life from him.

but also because hes has a really rough start in life he acts older than he is.

my stress and anxiety has hit the roof and i wanna approach this different so not to upset him but i struggle because i haven't had a good start either.

i dont wanna be a possesive dad but i also dont want him put in situations he shouldnt be in till hes abit older with a bit more wisdom.

any advice? lol sorry for the massive post x