So have you never completed the game before? Learning the mechanics and little tricks of the game are what make it seem easier. For instance, I had more trouble the first time playing on Normal than I did when I played Nightmare the first time.
In any case, although it isn't ideal you can get away with strength based dual wield rogues, and some people advocated them a long time ago (albeit before a fix for dagger damage). What is your current level and what specializations did you take (if any yet)? What talents did you take, and what weapons and gear are you using? How far back was the last save? If you don't want to start completely over, maybe consider going back one plot quest.
Since you have so much strength, I would consider Axe / Dagger, or you could even get away with Axe / Axe if you level up the dual weapon tree, although two full size weapons don't quite have as good DPS outside of offensive talents.
Start investing in Dexterity to get it to at least 30 or so, and equip the best dagger you can in the mean time in the off hand.
Since you have already gone strength, I wouldn't bother investing too much in Cunning since you are going to need the points for Defense. Low 20's or 20 pre gear is an ok number. This also means you can skip Lethality if you want.
After you get the Dex up you can either keep pumping Dex for more defense and dagger damage, or just go back to Strength. The latter of course would be best if you plan to dual wield 2 weapons.
As far as your character dying, since you said the hero is dying first it seems like the tank isn't doing a good job pulling aggro to begin with. Tank should be the first one to rush into combat, and should have Taunt and Threaten to help keep their aggro up. Also on the difficulties below Normal, there is extra aggro generated by heavier armor, so the tank should probably have the heaviest armor you can give them, which will also help him tank the damage.
Since your rogue can do DPS, don't get too crazy with the tactics and have the tank spam special abilities. The priority needs to be Taunt, and keep a couple sustainables up. So for instance Alistair might need to sustain Threaten and something like Shield Wall. He does not need to be spamming things like Overpower or Assault.
I don't play on console, so I am not sure what tactics are like on it, but if it is anything like PC then for Alistair something to get you started might be:
Self: Health <25% -> Use Health Poultice Most Powerful
Self: Any -> Activate Threaten
Self: Any -> Activate Shield Wall (or your best shield defensive mode)
Ally: Being Attacked by melee attack -> Taunt
Self: Being Attacked by melee attack -> Taunt
Self: Stamina >50% -> Shield Pummel
Enemy: Nearest Visible -> Attack
You get more Taunts and hold aggro better if he isn't spamming powers. You could set up a tactic for Shield Bash if an enemy is attacking a party member, or just leave it to micro yourself. Specialization talents can be added in if you get them. You can also adjust the stamina cutoff for offensive powers depending on what level he is and how much Willpower / total stamina he has. Also helps if you can give him something like Dead Coat of Arms, Fade Wall, Eamon's Shield or something like that for the stamina bonuses.
Also as pointed out above, the game goes a lot smoother if you take a healer, and Wynne is largely better for this than Morrigan, especially if you are on console and can't just use a respec mod for party members.
Of course, if the game is way too frustrating then you could start over. But it may not be a lost cause.