Are we being too strict with our 14 year old son?

[UK] Our son is an only child of older parents (I'm 60) with no local family and few of his own age living nearby. He has Nystagmus which limits his vision but he is not blind. He is just about to start the most important two years of school leading to exams that will be relevant for his future. He won't go to bed / sleep until the early hours sometimes and will fight us to stay up.If left to his own devices (pun) he will spend all day and night on his mobile phone looking at youtube videos about other people playing video games. Or, he'll be online with a friend of his playing Terraria, League of Legends or similar. He won't wash up the dishes (the water is too hot!) or clean his room and will stamp about when he doesn't get his way. His school work is terrible and we can't motivate him.So I use Kaspersky anti virus on the PC. It has parental control built in and we allow 3 hours weekdays and four weekends. This has him wanting to burn the house down! He has an LG G3 phone and on wifi he uses over 120Gb each month just watching videos. I'm looking at aps to restrict this time too, currently favouring Screentime at £30 a year.After all this, my worry is that I am smothering him. Should I let him be free to do what he wants within reason as 14 is a young man not a child? What are your tolerance levels with your 14 year old son(s)?Thanks. via /r/Parenting http://ift.tt/2bOGaG5