The very fact that having started the UPSC efforts in 2011 and that you are still thinking of it as an option to pursue is a clear indicator of your tenacity, commitment and a deep interest in IFS. I suggest you tap into this passion and interest and I am sure you will find the needed motivation to go for it. Make a list of all the good things that you want to achieve in an IFS role, visualize your life, write key points down in a very colorful manner or with the help of a professional designer/printer, hang it in an area where you spend a lot of time everyday. Additionally, since the UPSC exams might have an age limit, you can remind yourself that time is running out sooner than later.
Parallely, you would want to complete the LLB course and see how the internship pans out and what opportunities it leads you to. So that you have a good backup option as well. Of course, you will need to look at all of this in the backdrop of your personal and financial situation and what goals you have as a whole at this stage in your life.
Go for it! I am sure you will do very well.