Maybe try to find something that you and your family have in common?
Cookies?
I've heard of friends getting together, to make their own cookie recipe, and then they share, so they all have a can of different cookies.
I also hate shopping, but my 31 yr old daughter loves it. So we do a compromise.
We go to a cheap cafe and split a meal (we are small eaters) and then we do the rounds to the local thrift shops.
One place has a 'fill a bag for $2" which we both love.
I admit, I do love TV, I find it relaxing, and I like to be entertained.
I think many conversations may start off talking about the characters or plots from a show, but usually they progress to how you view similar circumstances in life. Similar to talking about what you read or watched in the news.
I like that you and your mom, are doing something together, without the sister.
Next time, maybe you and your sister can do something alone.
Because they are more similar to each other, you will probably always feel like the fifth wheel when you are with them.
Maybe find a new hobby, and ask if they would be to join you.
Making jams or preserves.
Making your own laundry detergent etc.
good luck