Assault my CV and leave it to return from dead

I would also change the ambassador bullet points: Bullet 1: "solved their queries" sounds so uptight and "service oriented" -> you weren't their bitch whenever they needed help were you? Use words like mentored / guided / advised. Your opinion and expertise was valued, not demanded. - Perhaps "School of Econ ambassador; advised incoming students on research and coursework and hosted information sessions during introductory visits, acting as a mentor to select students thereafter - as long as you did those things in any capacity as well as stayed in touch with students once they left their information sessions and became friendly with them thereafter you can consider that as mentoring. More importantly, people see it as you being a helpful leader that disseminates his expertise to others and keeps those connections even afterwards.

Bullet 2: It's ok but maybe change it to be a bit more specific similar to above. This will also help fill out some of your white space.

Agreed with others volunteer or do something to add one more compelling leaderships / EC to your CV

Also change "taught basic math and English" -> they are primary school kids we know you probably weren't teaching them linear algebra. Adding "basic" only makes the bullet weaker. Just say you taught math and english and let the reader form his own opinions on it.