Most women who exclusively pump start out pumping as much as humanly possible. A breastfed baby would normally nurse 10-12 times a day, so that should be your goal, to pump that often. To bring in a good/full milk supply with just pumping, you really need to rent a hospital grade pump and pump religiously every 2 hours for 24 hours, then every 2-3 hours during the day and 3-4 hours at night.
Skipping pumping sessions to get more sleep right now is a bad idea. right now your body is growing all of the ductwork and prolactin receptors within the breast as well as milk making aveoli. These things grow based on how often milk is emptied from the breast. Getting these things all in place within the first 4-6 weeks by very very frequent nursing or pumping will help you to be more successful. Studies show(and my 12+ years of giving breastfeeding advice bears out) that women that back off on pumping frequently before their supply is well established tend to have milk supply issues--they may be fine until the 3 month growth spurt where your hormones stabilize significantly and milk becomes hormonally driven. So it is important to pump as.much.as.you.can right now.
But more worrisome than low supply or not pumping often is the OP says baby is hard to wake and very sleepy. AT 2 weeks you should see a bit more awake baby who actively nurses or eats and then sleeps, but isn't super sleepy. Has all jaundice cleared baby's system and has baby regained their birthweight? Those are the questions to be answered that have me a bit concerned.
If baby is getting enough to eat they will have at least 6-8 wet and/or poopy diapers a day minimum. but if things are going well they may have 10-12 wet and or poopy diapers, one at every feeding like a little bird when they eat they poop/pee. If the diaper count is low, then increase waking and feeding baby more often. A jaundiced baby will be extremely sleepy, also a baby that is getting food but not quite enough food will be more sleepy and will make less poops as they will be absorbing everything they are eating and may not poop many times a day which is normal.