yea nitrogen usually is minimal in bloom nutrients for all the reasons you said. Plus too much of it during the start of flowering can make the sex male
Your yield is definitely going to suffer.
Like I said those flowers look 2-3 weeks old.
So there growth has been severely stunted by lack of nutrients.
All you can do is hope that they get bigger before they start to show signs of maturity.
nature usually sets itself out the right way. just better luck next time i guess. if you want to increase THC, in the last week or so dont water at all, by doing this the resin glands will work harder and the trichomes will get bigger