Answer: Thank you for giving us so much background information. This certainly helps in trying to answer your question. I particularly was interested in knowing that you enjoy your job and the people at your firm. I'm sure that makes it a bit more difficult looking for a new job.
You are absolutely correct when you say that it is too soon to move in-house. With only six months of law firm experience under your belt, I doubt that there are any in-house positions that would make sense for you at this time. Besides, as I have said many times before, I believe that you would be much better off staying within the law firm side of practice for at least a few more years before even considering the in-house route.
I am so sorry to hear that you are miserable. It is simply terrible to dread getting up in the morning because you hate your job. It is also sad to think that you are not able to spend as much time as you would like with your two small children. There is no question that they grow up fast and when you are spending most of their waking hours at the office, you miss a lot of those special moments.
Let's try to walk through a few of your issues. You say that the workload is more onerous than you had expected. Were your expectations realistic? Did you summer at this firm? If so, are the hours expended now different from the impression that you had during your 2L summer?