Hi, Shannah - I was going to reply privately, but I thought we should all share ideas - this is a very frustrating situation for new moms with premies!!
Most of the NICU graduate moms I talk to after baby has gone home tell me that it usually takes anywhere from 2-6 weeks for their baby to be able to breastfeed well. The more premature the baby was, the longer it seems to take for this transition.  "Wearing the baby on your body"  skin to skin seems to help more than anything.  The stories the moms tell me usually go something like this:
"We were lying on the couch and I was holding him skin to skin, watching TV.  He woke up and started rooting around - it wasn't time for him to eat, either.  Even so, I offered him the breast and he began sucking.  He has gradually gotten stronger every few days and able to take more from my breast".
I  would encourage you to rent a  Baby Weigh scale or some similiarly sensitive scale from a lactation consultant in your area.  Ask her to show you how to do pre and post test weights.  This way you know how much your baby takes during the feeding.  If he is spending 45 minutes suckling and only gets 1/3 of his feeding or less, you may want to temporarily limit his time to about 30 minutes at breast, then let him complete the feeding from the bottle or another method of feeding that you are comfortable with, such as cup or finger feeding.  This will cut down on the amount of time he is spending working for his food, increase his sleep time, and improve weight gain due to extra time spent in sleep and less expenditure of calories.  Once you see (by test weight) that he is taking more from the breast, he can stay at breast  longer and you can begin to eliminate supplements gradually and let him feed more frequently if he desires.
Try  pumping for a minute or two (before you put baby to breast) in order to bring down milk before he latches on.  This way, he will receive milk from the start, without having to expend precious calories "working" to bring your milk down.  
I would urge you to see a lactation consultant as soon as you can so that she can assess positioning - some times babies look like they are breastfeeding efficiently, but they are fooling us.  Your LC may have a few tips for you.
I don't usually like to tell mothers to bottle feed EBM instead of putting baby to breast; but if your husband can help you for one feeding during the night - you could pump while hubby feeds baby.  Saves some time, you go back to sleep, which you desperately need right now.
The world of a premie household is a different ballgame altogether, isn't it?
I'm hoping other NICU LC's out there will have some other ideas also.  Blessings on you and let us know how you are doing!!

Dani Hudspeth RN, BSN, IBCLC
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