At level 4 you should be good numerically for the underdark, it's just kind of a nasty place to be. Feeling uneasy is the point! That said if you aren't feeling it just go back topside, you will get a HUGE power boost at level 5 that will make the first act of the game much easier.
Also since this topic is about respeccing: you can also respec the party members, but as much as I love to minmax I don't think this is necessary and the default builds are fine for a newbie...aside from Shadowheart whose build I think is criminal. They gave her a stealth-centric build which is cool if you like group stealth but nearly useless otherwise, either way it's just very unintuitive if you are new to the system and is a mistake. I would HIGHLY suggest respeccing her, changing her Domain (Life is a good one if you'd like a strong healer but Light and War are also strong), slapping the heaviest armor you can get on her, and pumping her Wisdom as high as you can get it, then Con and/or Strength.
Trust me on this, they did my girl so dirty
I definitely did not forget to put the 2020 GOTD Guru winner,
azuarc
in my sig!
https://www.backloggd.com/u/HDT/