Well it is to early to say as JEE is one of the trickiest exams and you can't judge anything about the results till it is actually out. SO I would recommend that you wait for another week for the Results and decide on this. For further information as to you can get a govt. college or not refer to the JOSAA websit to check for the last year's cutoffs for various institutes.

Akunuri with your 100 marks in JEE Advance exam 2018 under the SC category with the previous data of marks vs rank distribution you can expect a rank to be around 1000 in your SC category and which is expected to get better with the fall in the JEE Advanced cut-off due to increase in difficulty in the paper and a paper without any errors as last year 18 marks were given to each student due to error in the questions.

So, if you are able to get a rank in the range stated above then you can surely get admission in one of the new IITs and maybe if the luck favours then in one of the non-conventional branches of one of the old IITs.

Feel free to ask if you have any more queries. All the best!!