FWIW I think that, with your background, you are doing really well.
It's incredibly difficult growing up without parental approval because it's natural for children to seek that and every rebuff and knock back is a serious blow. It's very painful but as you'll know from Stately Homes a lot of people who have had a childhood like this stop having contact with their parents as they get older, the hurt becomes too much to take.
It doesn't sound as though you're able to go NC with your family at the moment, but it's important that you recognise the damage to you self esteem that you suffer when you're with them. I would urge you to limit your time with them and, when you do have to be with them, try to spend that time with the children rather than the adults. Don't answer the phone to them - let them leave a message so you can listen when you choose and compose your thoughts before responding. (A downside of mobile phones is the way that people can intrude unexpectedly on your day). The adults in your family have followed your mothers lead and taken advantage of your good nature : time with any of them is probably not good for you at the moment.
I'm so sorry about your father. There's no good age to lose a parent but at the start of secondary is particularly bad. You have done amazingly well to go on and go to University in these circumstances. Congratulations - it sounds as though he would have been proud of you.
Well done for keeping your room tidier, keep it up and keep tackling the laundry pile. It's a never ending task but you will get 'flow' from it.
That's brilliant that you said 'yes' and went clubbing. Even if clubbing isn't for you there's the whole journey there and back and the getting ready before and talking about it afterwards. Keep saying 'yes' to clubbing and other non family things - it'll engage you with life and cement your friendships. Stick with it and other things will replace clubbing in time.
It takes a lot of courage to admit to yourself that you're unhappy with your life and want to make changes. I am so impressed with the efforts you are making and the way you are engaging with the suggestions on this board. Keep taking the small steps and it will slowly come together. If you were my daughter (and you're young enough to be!) I would be so proud of you. x