Hi J.!
Breastfeeding is so important in your babies long term overall health, I suggest that you continue doing so.
Nowadays, there are a variety of breastfeeding equipments to save breastmilk in the fridge for future use.
Many times babies wake up during sleeping time because of gas caused for poor formula digestion. Always take out the gas after feeding her. As you mentioned, the formula is cow's milk based. It is most probably that your baby is showing an allergy reaction to it. To most of us cow's milk help develop health problems like sinusitis, different kinds of allergies including diarrhea. Also look for the kind of iron added because to aggravate the situation this may cause intestinal irregularity (constipation).
Finally, there is no substitution to breastfeeding and you could continue up to 3 years old. This may be a little bit uncomfortable for different reasons, but believe me I have seen the difference between the health and energy of a breastfed child and the one who barely received breastfeeding.
This without mentioning tons of hours lost in doctors office, hospital, money spent on this and in medication cost and risks in your babies health for medication use or even her presence in a hospital environment. Nature has all the answers. All we have to look is for its answer.
If your situation is that your milk production has decreased considerably, motivate your system to produce more milk practicing breastfeeding. If you are no longer producing milk write me to look for different foods and supplements that will help you on this.
Thank you for the opportunity to be of help.
God Bless You and your Family!
A.