Personally, I've always found it harder to study at home, because it's too comfortable and there are too many distractions. Very easy to say, "Oh, I'll just take a break for 5 minutes and [check my email/get a drink/see what's on the news/get the mail/put my laundry in the dryer/whatever]" and then the 5 minutes stretches into 30 and when you finally do drag yourself back to the books, you're not really concentrating.
...or maybe that's just me, because I am a procrastinating, underachieving slob with terrible study habits.
When I really
needed to get something done--study for an exam or for finals, write a big paper--I went to the library and locked myself away in a study carrel. Is it possible for you to carve out some time every day--even an hour--or a chunk of time once or twice a week to do this?
Also make sure you organize yourself before diving in. There can be so much material that it's overwhelming. If you need to do a lab write-up for one class and read 2 chapters for another class and study for an exam in the 3rd class, you really need a plan of attack. Divide it up into manageable tasks, sort it in order of importance. Set a time frame to complete the task.
Part of it, too, is just learning to compartmentalize. Tell yourself that when you're studying, you're going to concentrate completely on studying; and set aside some time at home to concentrate on your family. It kind of sounds like when you're studying, you're thinking about your family and when you're with your family, you feel guilty that you're not studying.