It is normal for a breastfed baby to reject a bottle. They are not used to the feel of the bottle, or the formula. Better to pump your breastmilk than begin to feed your baby formula which is not as good as your breastmilk for your baby. If you can breastfeed your baby, why not do it. It is better for your baby and you will save about $3000USD a year...
Babies primary diet can be breastmilk, technically almost til age 3 according to the World Health Organization. I know some women who did not hardly start any solids until their child was one year old.
That said, I know you must be tired. I am also tired. My breastfed son still wakes up at night and only now, at 16 months will I begin to wean him from the night feedings. Honestly, it is exhausting, sometimes he wakes between 2-4x, but this is simply habit at this stage as he is quite big. On the up side, my baby has only been sick once ever his whole life, and this was when we moved to HK. He is extremely healthy and happy. Remember that it is perfectly normal for babies to wake up frequently and often many babies change sleeping patterns as they get older. You might try to read books by Dr. Paul Fleiss on sleeping and nursing and check out, if you can issues of Mothering Magazine.
But, if you are talking about a very very young baby, you have to make sure that the baby is getting enough hind milk. Try to keep him as long as possible on each breast. The foremilk is the protein, the hindmilk is the fat milk and comes in after 2-4 minutes and is the stuff that will fill your baby up. The more hind milk he drinks, the longer he will go without frequent feeds BUT note that bottle fed babies do NOT have to feed as frequently as breastfed babies--this is a medical fact.
Absolutely you are doing the right thing making breastmilk the primary part of the babies diet, even through one year. There is a direct link between the length of time the baby is breastfed and INTELLIGENCE level--many recent scientific studies, in fact. Please also look at La LEche LEague website
http://www.llli.org/ for tips on breastfeeding and facts...always best to look beyond the forum.
Good luck!