I'm curious to know why you feel the need to wean her from bottles or from formula if she is enjoying both and isn't showing signs of being ready. The one year old mark is not some magic number to base a parenting decision on. Every child is different. Bottles and formula will not suddenly start to damage her once she hits 13 months old, nor will weaning become harder.
If you really feel the need to wean her, I'd pick ONE thing do wean her from gently. Either bottles OR formula, not both. And some kids will refuse to take sippy cups or drink whole milk, even if you do the cold turkey method, so don't assume that she will eventually take something new just because her old isn't offered to her anymore.
If you are changing from formula to cow's milk, start by mixing a little cow's milk into her already mixed formula in her bottle. Increase the cow's milk and decrease the formula a little each day. She probably won't even notice the switch if you do it gradually.
If you are switching from bottle to sippy cup, try to limit bottle to her comfort times like first thing in the morning, before nap, before bed. Encourage formula (same temp as the bottle) in a sippy cup for snacks and lunch. Then, each week, cut ONE bottle feeding out until you aren't doing it anymore.
Each child is different, so you need to be in tune with her personality. For some kids, cold turkey really is the best option. They get mad for a minute, then get over it and move on. If your child is NOT like that, gradual is best :)
Good luck! And remember, I'd ask your pediatrician the concrete reasons behind the need for the switch in the first place.