Formula Supplement Recommendations

Right now my baby is 2 months old about to turn 3 months. She is mainly getting breastmilk but we do supplement with Enfamil Premium Newborn 0-3months Pre-made formula. I am going back to work next week and will be pumping at work with the hopes of being able to keep my supply up and having enough for her while I am gone. I am wondering what formula would you recommend I supplement with after she turns 3 months?? She is gassy sometimes but we use gas drops here and there and it helps her right away. She does spit up but only when she eats too much.

Thank you!!