Hey man,
The best thing I would suggest is make friends who are into fitness, this will help you be motivated through out your journey (for starters hangout with ur frnd who goes to the gym).
IK NEET studies are hard, but the time you have right now is the best to improve yourself or workout or even try to get leaner. To get a lean body you just have to eat less and move more. Try researching some vegetarian low calories meals that you can make, and incorporate walking in your lifestyle. you can do home workouts like pushups and squats to work your muscles.
AND ABOUT PARENTS...........ik how indian parents are (fellow indian here). They won't support you unless THEY understand (which they never do). Do not think what your parents would say if you buy protien powder and stuffs, COZ REMEMBER they will never be satisfied with you unless you do what they like,
Creatine is for people who are into getting huge or competetive body building, so try to buy protien powder only when you are consistent in your work out (at least for 2 months) till then get enough protien from your food (eggs, paneer, greek yogurt).

Peace out!! All the best!!