All of the above is correct. It's basically just eating more. If you're doing that much kickboxing you can pay less attention to assistance work for certain attributes & body parts but that's really getting into nuance. Frankly you just need 2-3 (probably just 2) weight session per week, but constantly overeat during the week. Probably somewhere ~750-1000 cal over maintenance. It seems like a lot but you'll need it. Think "gallon of milk per day".
From my experience, training in the morning makes it easier for me to eat during the day. I'm hungrier and I feel like everything I eat is going to help re-build and prep me for the next day. Also depending how much training you're doing (do you do extra cardio? lift now? run any? etc) you'll need to de-prioritize that stuff for a bit. I'm not saying stop, but for instance if you run 30min now, going to 15min really won't hurt you as long as you stay consistent.
You just don't want to have to re-establish the movement pattern later so keeping it (running, bagwork, etc) in small doses serves the purpose. You'll adjust much faster when you get back to training kickboxing full time than if you stopped completely.
If you REALLY want help:
Step 1- KEEP A FOOD LOG.
Record every meal you eat, the approximate calories & macronutrients (protein, carbs, and fats)
Step 2- RECORD EVERYTHING YOU EAT FOR TWO WEEKS
Snacks, Drinks, everything. I recommend getting a tiny notebook you can keep with you and developing a system that's easy and quick to record. Something like this...
Step 3- POST YOUR RESULTS HERE
We can help you a great deal more (and you can help yourself) if we have an idea of what you're currently doing for training and nutrition. Right now it's like shopping for a car but not having any money. We don't know wtf budget we're supposed to be working with.