Lets say the you average 2400 cals/day and you want to gain weight. It is simply eat more than you are burning and you will get bigger, eat a lot more and you will get a lot bigger (not a good thing).
If you are keeping track of everything, which it looks like you are, just start to carefully increase your daily total in through clean foods. up 100-150 cals/day for a week or two. See how you feel. If nothing happens, and you’re feeling weaker then up it a little more. Any changes should be in moderation.
Nutrition can be as complicated or as simple as you want it to be.