In Normal life, you have to brief your words, ignore unnecessary sentences to avoid being weird. Ielts on the other hand: just keep talking sh*t as long as you can Your score will be 67 out of 10
I think you have made it a little complicated. Instead, you could have said, "Yes, I have two siblings. To be more specific, I have an elder sister who is pursuing her master's in (subject name) and a younger brother who is preparing for a competitive exam now." I feel no need to say, "Our family consists of five members, including me." Also, "That makes a trio of us."