Yeah I could for sure include a few combos of flush draws but then i haven't included QQ which I think could sure be in there too, so it probably evens out. Besides I'm ahead of flush draws so assuming he lets me showdown my pair when he misses they could even make this more +EV.

These two examples you are confusing are essentially the same thing. Just use that formula I used to work out how often your bet size requires him to fold in order for it to be +EV (assuming you have no pot equity that is, obviously the more pot equity you have, the less fold equity you need so this number will be less than shown by the initial calculation) Then compare this with how often you think he does fold based on analysing his range and how he plays it. Tweak the 2 until you've got the lowest bet that folds out enough of his range to be the most +EV size.

You obviously don't do this at the tables or anything, you're doing these exercises to get a really good feel for how likely a bet is to be +EV. I didn't get my bet size exactly right because that's pretty hard and takes a ton of practice.