If you have interest in medical courses then only prepare for NEET 2020. The age limit for general category is 25 years for NEET (it was announced that above 25 years age students are also allowed but the confirmation has not came from the court).NEET can be given any number of times. So you can give NEET 2020. 

It's a little difficult to get admission in MBBS in government colleges but not impossible. The cutoffs for MBBS in government colleges are high (580+ on 720) but this can be achieved. 

Other courses like BDS (Bachelor of Dental Surgery),  BHMS (Bachelor of Homeopathic Medicine and Surgery), etc are the courses you can get by giving NEET. Do you have interest in it? Would you like to study any of these courses ? If yes then go for NEET. 

If you have interest in engineering then there are entrance exams which you need to give for it. The entrance exam depends upon which college you want to take admission in. There are many branches in engineering too for example computer science engineering ,mechanical engineering, civil engineering, etc. Computer Science engineering is about building application, programming and many more.  

Now for pure sciences you can go for BSc in any of the subjects you like (Physics or Mathematics or Biotechnology or Chemistry or Microbiology, etc). After which you could go for MSc in that subject or any other course. 

Choose wherever your interest lies. Medical,  engineering, pure science are completely different from each other. These also have branches within them which are also different. Where does your interest lies and what would you like to do in future? 

If you still have any queries feel free to ask in the comment section down below.