Need Some Advice On Parenting..

Your fears are justified and so is the behaviour of your tween/preteen daughter.
Compared to 20-30yrs back, kids and especially girls are attaining puberty early. You should be prepared anytime after 10yrs and prepare your daughter too and educate about menstruation and menstrual hygiene.

Now you may think i am diverting the topic but no, let me tell you... its all about hormones.
In babies, around 3-4months they have a huge growth spurt n hence suddenly become irritable/fussy/ cry nonstop n do not sleep. Same happens during adolescence only that since the kid is older, she/he uses harsh words/anger/ talk back at parents to express their feelings.

This is the time to handle them as gently as you can. Many parents would feel they are patient but that might not be the actual case.
Indian parents especially knowingly or unknowingly tend to compare their kids with neighbour kids or their school friends or heck even with their own siblings and it might lead to lot of self doubts, insecurities and frustration in kids.

The talking back at you or throwing tantrums is all because they are still immature and do not know how and where to channelize their frustrations or feelings.
How to handle?
You would be the best person to study about your own child's behaviour and her thought process.
1. Do not ever compare her even with your other child(her own brother or sister)
Nor with other children.
2. Do not set expectations like she should be topper or get gold medals else she wont make it to good Universities or have a good career... this is where most parents push their teenage children into depression even if not done intentionally.
Instead discuss with her about what subjects she liks and which she doesn't like and why and try to use innovative methods to reduce her dislike and generate her interest in that subject.
Assure her that no matter how much she score, her parents will always love her and support her in this world.

3. Do not show disappointment if she say, scores just 50-60% and you expected it to be 80-90%. Instead applaud her and encourage her to improve herself by boosting her confidence and slowly encouraging her to work on her weak points.

4. If she is still not interested in academics but she is great at some other extea curricular activities say writing/painting/singing/sports/dance/etc ...always encourage her praise her to do well in those activities. It will help boost her morale and also she would have confidence in you as parent.

5. This is the age to ensure she is slowly introduced to what girls go through during hormonal surge, talk about boyfriends, good touch and bad touch, setting boundaries etc.

6. About tantrums, don't react, don't scold her, don't blame her. I know its easier said than done but it's very important. Once she is calm, go to her room make her favourite drink loke hot chocolate or something she likes, gently pat on her head with smile and say you love her the most .
She will take time but eventually come around.

 

Mostly kids will be very moody and go through a lot right before reaching puberty. I literally saw how my elder one broke down and was crying at the drop of a hat when she was 10+. We had no clue what was going on, she was not the kind to cry or show her emotions in public even when she was a small kid. But she was crying in a public place, a relative's house, everywhere for no reason at all. Then in a couple of months, she got her first period. Even today, right before she gets her period, she is in a different mode. Now my DD is 11+, in middle school, she has suddenly become so responsible, very perfect, takes her grades more seriously than ever before.
It's definitely difficult to understand what's going on with these kids. So just remember this is only a PHASE your DD is going through.

 

OP

You already got good suggestions about how to handle and not to expect about academic achievement like typical Indian parents. Lot of teenagers are struggling with many mental health problems. What additionally you can do is give her more plant based food. you can make smoothie with fresh fruits and power greens and keep it in fridge. Kids usually like cold sweet smoothie better than our Indian curries.

 

Also most important thing if she doesn't have smart phone or gadgets keep her away from it as much as possible. Involve her in some good activities like extra curricular or religious or fun sports etc. Don't push too much about academics for now. My kids are big now but I made some mistakes which I regret like comparing one kid to other or not talking positively always. I had my own health problems like menopause plus younger kids teenager tantrums plus husband's mid life crisis. I should have just ignored my problems and focused only on kid's mental health during puberty. Kids are very sensitive although they don't show it. In school they have challenges like fitting in, peer pressure, homework, exams etc. Home and mother should be their comfort place. Later you will enjoy fruits of your patience and hard work.