A-town:

Only Nigerians make a big deal out of english grammar. English is our second language so stop emphasizing unnecessary details and correct the person jare.
A lot of americans/britons can't speak/write proper english.
At least most of us can speak our languages. Even those that are not fluent still know how to use words in our local languages. I haven't seen anyone wey dey "tabon/ blow grammar" in Yoruba, Ibo, Hausa or pidgin. Kini big deal sef.

To answer your post "How to be confident around women"
Just ignore them. Do you know that a lot of women are very timid. Do you know what happens to a womans ego if you approach her, give a compliment and just leave without trying to get with her.
Ignore them and they'll start appreciating you juh,

What women timid? Certainly not naija women. . .