Hi LunaticAnagha,
It's great that you have both entrepreneurial and non-profit experience under your belt, in addition to your work experience. Under the 'work experience' section of your resume, you want to make sure that your primary professional experience is clearly highlighted. Sometimes when you have a bunch of roles that have overlapped during the same period of time, this can be confusing to the reader and muddles your message in a way that doesn't truly highlight the skills/knowledge you've gained and the accomplishments you've achieved.
Your full-time work as an engineer belongs under work experience, for sure. Your work as a co-founder of a non-profit can also go under work experience, although you will need to decide which should appear at the top of work experience section. I recommend having your full-time position be the spearhead of this section, given it was in a full-time capacity and you have spent more time is this particular role. Your non-profit experience can then go under your engineering position. Filling both of these out with 4-6 strong bullets will give you two solid examples of work history and many examples of the skills and accomplishments you displayed within each bullet.
As for your Teach For India position, as it is part-time work and also of a civic or community service nature, you could put this under an 'additional' or 'other experience' at the bottom of your resume. Let me know if you have any follow up questions. And best of luck with your resume and apps!
Sincerely,
Way Lum
ZoomInterviews
https://zoominterviews.com