My LO is 14 weeks, and is fed almost exclusively with ebm as bf isn't very successful, and is mostly for comfort now. My info mainly comes from the John Radcliffe bf clinic in Oxford, though some is personal experience and may differ from you.
JR advice is that you need to pump 6 times a day, but there's no need for one to be at night. If you have spare milk, and anyone to help, get someone else to do the night feeds and only to wake you when the last bottle is gone - sleep is essential to successful expressing. Expressing too often can make your boobs sore, so try not to do it more than 3 hours together. Lansinoh is still important, as expressing can be hard on your boobs, too.
You don't need a routine as long as you pump 6 times daily - babies are best demand fed, after all. But DO pump off both breasts, and pump until you aren't getting any more milk. You can pump one till the flow stops, then the other, then the first and then the other again. Your boobs still work on supply and demand, and your freezer will be there for any excess, so empty the boobs and thereby place the next order.
Don't use formula as a guide to bm, as it takes twice as long to digest formula because lots of it go straight through! So they theoretically need a lot more formula than bm, as so much more gets excreted. Having said that, my son is a greedy chap and snarfs far, far more than the bf norm. Basically let your baby eat what s/he wants and on demand, and you'll soon work out their appetite (though even then he can vary hugely in what he wants, feed to feed).
I posted what I've found helps me supply-wise near the end of this thread and so did another express-feeding mother, whose points I totally endorse as well.
Fenugreek can be taken as long as you feel it helps, I still am, but I have to admit I couldn't face blessed thistle tea (still in the bag...). I know other people use Domperidone, too.
I'm starting to think there should be a MN support thread for us lot - seem to be a fair few, quietly expressing away.