you don't need ir/uv....if you want, a simple 25w from amazon will do. Only 2 hrs a day at the last 2 weeks will do.
https://smile.amazon.com/gp/product/B088R9MS91/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
you are not doing anything wrong except maybe over worrying / over thinking it. We tend to live in our tents in the beginning, micro managing. Expect problems / failures and sometimes, just let them do their thing. Of all the things we do, we WAIT more than anything. Propagate seeds - wait, sprout - wait, seed them - wait, veg them -wait, flower them -wait, finish them - wait, harvest them -dry and wait, cure them - wait some more.
Nutrients - do not switch over until you have a definitive 2-3 weeks of flower. It ain't broke so don't fix it
You do want to do preventative - have the environment prepared or inoculated against issues that arise in mid to late flower. Mostly MOLD.....if you are using 3-5gal in a 4x8 and 14 plants...that is a LOT of transpiration and humidity can crop up and bite you in the butt. Make sure you got good air circulation and probably nano-micelle (organic based) mold prevention on the leaves in addition to good defoliation. You do not need a ton of fan leaves, just a ton of buds....lol
Some growers use a foliar spray of milk/water at 1 part milk to 9 water as a mold prevention. This is ok but NOT ON BUDS. That is why I use nano-micelle. I can spray that all the way to harvest and on everything / everywhere (tools, intake / exhaust tubes, fans, walls, containers, etc.)