the volume of water you add shouldn't chane unless you water at a different point than normal. Always saturate the entire substrate's volume - however much it takes. If you re-irrigate at same loss of weight from pot, it will require same volume... best to wait for top layer to dry before re-irrigating. promotes good root growth (less superficial) and reduces risks of pathogen/pests.
if you have proper drainage qualities, it's very difficult to 'overwater' ... frequency tends to be an issue more than volume given.
If habits don't match that, may or may not be part of the problem but good idea to fix.
This could be one of many things. More detials can help eliminate possibilities. e.g. if this only curls down last couple hours of day it could be related to lights.
Too much N can do this, but leaves don't look too lush nor glossy.
I'd say drop your N 10-20% and see what happens.. looks like it's entering bloom anyway. I would assume at this stage your fertilization is providing most of the nutrients. it may take a few irrigations before the full effect is achieved.. or get a little runoff waste next 2-3 fertigations to speed up process (dump wste water outside or down drain).. 70/30 should be okay for a decent runoff. a little more perlite might promote better roots (*bugbee) and be more robust to such things if you do need to adjust formula midstream in a time sensitive way. you have time to be patient here, fwiw...