I hate to say it, but things may get worse before they get better...these pesky babies have a bad habit of shifting their sleep patterns just when you think you have it sorted!
The general wisdom of BW aims for about a 12 hour day for the first few months, or thereabouts. I would be careful about setting up a day length that is too much longer, as when your little ones get a bit bigger they will need an earlier bedtime and it may be tricky to adjust. I really, really recommend setting up a strong bedtime routine which is the same every day, as in my experience this resets the clock, no matter how well (or otherwise) the day has gone, and gives you the best possible chance of decent night sleep!
Good luck -- there is some great advice on this site!