Can anyone help with future mother in law?

Hi everyone I'm really new to all this. I've been with my boyfriend for 6 months and we are really happy together. Sometimes I become very annoyed with his mum. She is very controlling and he has to ring her to ask if he can stop round mine and he has to clean the house and on certain days she won't let him leave the house. He is 27 and I'm 19 and I can totally understand her feeling protective over him but we plan on moving in together once we've saved up enough money and fully prepared ourselves. We are both very responsible and understand what it takes to live together. We know it won't be easy but the best we can do is save our money and work hard. I'm scared his mum won't let him leave. I know his mum is really important to him but sometimes it feels like I'm pushed to the side and forgotten. My parents feel we are very well prepared and they trust mine and his judgement. My boyfriend wants to move out as soon as possible because he is becoming fed up with his parents overprotective behaviour. His 18 year old brother is allowed to come home after midnight but my boyfriend is expected home at 10 thirty. I'm not sure if his parents approve of our relationship because they often say that we are not right for eachother but we are really happy together. We do disagree at times but we talk things through and his parents are always arguing. Me and my boyfriend don't hug eachother in front of his parents because it seems to upset them. I'm not sure what to do. I'm at a loss. Why are they so interfering and over protective and why do they treat my partner like a child at his age. Can someone shed some light please