I was in almost the exact same boat in Wrath. 10-man, cleared everything on normal with a few easier heroics thrown in (lootship, XT, Jaraxxus, etc.). We raided two nights a week, 4 hours a night. I fully considered us a casual raid, however. That has nothing to do with how much we played, or what we killed, but with our attitude. If you couldn't make it to raid, that was cool. Just tell someone. It was just pure fun, very little pressure. The divide between casual and hardcore, to me at least, is purely based on how you approach the time spent, and how you treat your fellow raiders.

That's basically how I feel about it as "casualcore." Back in Wrath my guild only did well in 10-mans (too much pugging to make 25s successful) but when we raided we raided. We wiped on fights over and over before finally getting them down; sure, it was on normal mode (to begin with) but you still got that same rush. And once we got a fight down it would take a really bad night to wipe to it again. And we only ever raided one, maybe two nights a week tops, but I still remember full-clearing Naxx and ICC on normal, and then doing some heroic modes in both Ulduar and ICC.
We never got that Yogg kill back in Ulduar, something which gnawed at a few of our members, but we were all great at what we did and put in the effort outside of raiding to do well in it. We expected results from ourselves and others, something I think a truly casual environment wouldn't do (if it's "just for fun/content") but we always had a blast, joking it up between and even during boss fights, never having loot issues. Ah, good times. I miss my old guildies.