I don't think you'll run into any times when you have to heal. If you want to DPS, that's what you should do. Especially if you are much better at it. You might lose a healer in a FP or something and someone might want you to switch, but if you aren't comfortable it's probably not gonna go too well. If by "not very good at it at all" you just mean not quite as good as DPS, maybe you should give it a go. It just takes practice.
I've played all three (50 sorc and 50 sage (lol, and 42 sage and 38 sage), 50 operative and 37 scoundrel, and 32 mercenary, all healing only) and in order ease of use (aka easy to learn and play) for me it goes: (1) Operative/Scoundrel (2) Sorcerer/Sage (3) Mercenary/Commando.
All that above is from PVP perspective. I have no idea where merc/commando heals are at in PVE since 1.3 came out. All I know is the number of great merc/commando healers in PVP is very small, and from playing my own it seems to take a bit more work due to the hard cast reliance compared to the other healing classes to output the same kind of HPS. What I'm saying is, you might not suck. It might be the class itself isn't a good fit for you and healing. It's a bit more of a learning curve IMO, and healing is kind of a mindset anyway.
Yeah. I mean, I've always played DPS, and the rest of my classes are DPS, so I just selected Mercenary cause I like the dual pistols.. (that's why I chose slinger over scoundrel...). But GAF Empire is, from what you guys tell me, dead, and I'm not in a guild on the Empire side, so when I get to level 50 (only level 26 or so right now), I figure if I was able to heal, I might be able to find groups easier for PVE stuff.
Ugh why is the Inquisitor storyline so much better than the Consular one? Only thing stopping me from playing my GAF character more... That and Qyzen is kind of a lame-o too.
From what I hear, Consular's story gets much better later on, while the reverse is true for Inquistor. I'm enjoying the Consular story, especially as a darkside, lol.