You are welcome.
On the contrary, it may work to your benefit to involve his family to some degree in your dating life.
His mom and sister don’t really know you.
As far as they are concerned, you are someone who is interjecting into their tight family circle, like an interloper or invader.
If, for now, you make it a point to hang out or go out with your boyfriend and include his mom and sister, they will have an opportunity to get to know you.
Not only will they get a better sense of your personality and who you are, they will also be able to get firsthand evidence of how well you treat him.
Going out or hanging out like this, on a semi-regular basis for now, could help to ease all the tension that is going on between all of you.
It could get both his mom and sister to be more accepting of you and like you as a result, thereby reducing the amount of stress they put on your boyfriend in terms of their disapproval of you.
As his mom and sister become more comfortable with you and consequently trust you, they will not be as involved in your dating life and you will be able to have more freedom with your boyfriend.
So, this strategy will take some patience on your end.
However, with a less stressed boyfriend, you will most likely see more effort coming from him to chat and meet up on more frequent dates with you.