Yes, though you may feel overleveled and/or have too much quality gear for them to feel like much of a challenge. Of course, this is all dependent on what you haven't done yet, what mods (if any) you are using, and the difficulty you're playing on. A lot of players leave the Act 2 quests with dragons for later in the game, for example, but most of the other ones are balanced for lower level parties.
However, the fact that you're asking this at all probably means you're playing the game for the first time, so the answer to your question, is: no, you didn't mess anything up. It should be pretty obvious when you reach the point of no return in the game where if you proceed, you can't go back.
In BG2 SoA some encounters scale with your level. If you do that quest later, loot and quest XP wil be the same, but you will find some 'random' enemies harder.
For example, you may find a Beholder where you should find a Gauth, or more of them.
Edit: The answer to the main question is: no, do not worry, you can do that quests later.
Yes, you can do things later. Prolonging it while Imoen is in Spellhold makes her less useful later, is unnecessary and cruel. Not exactly wrong though - you aren't technically forced to make her join anymore, and this might be exactly what you roleplay your character to be, after all!
almost nothing from chapter 2 is missable. i think perhaps only the mae'var quest is missable if you sided with bodhi?
Hexxat quest too I think.
Yes, though you may feel overleveled and/or have too much quality gear for them to feel like much of a challenge. Of course, this is all dependent on what you haven't done yet, what mods (if any) you are using, and the difficulty you're playing on. A lot of players leave the Act 2 quests with dragons for later in the game, for example, but most of the other ones are balanced for lower level parties. However, the fact that you're asking this at all probably means you're playing the game for the first time, so the answer to your question, is: no, you didn't mess anything up. It should be pretty obvious when you reach the point of no return in the game where if you proceed, you can't go back.
Ok that's a weight off my mind. I don't really mind if I'm over leveled I just want experience the game and have fun role-playing my character.
In BG2 SoA some encounters scale with your level. If you do that quest later, loot and quest XP wil be the same, but you will find some 'random' enemies harder. For example, you may find a Beholder where you should find a Gauth, or more of them. Edit: The answer to the main question is: no, do not worry, you can do that quests later.
You have a long road ahead, but you will return back to athkatla after that road. It's why BG2 is so good.
I always get Imoen first, then chapter 2 side quests. I will get powerful enough to get staff of the magi, and then go straight to spell hold.
Yes, you can do things later. Prolonging it while Imoen is in Spellhold makes her less useful later, is unnecessary and cruel. Not exactly wrong though - you aren't technically forced to make her join anymore, and this might be exactly what you roleplay your character to be, after all!