Hello.
You should calm down to start, because your anxiety can affect the baby. By your behavior, your daughter suggests that she is missing your sincere attention. Even if the difference between children is large, it is possible that she still did not receive the attention and love she needed. The child is now possible crisis of 6-7 years.
Here is a childish jealousy. If you scold her all the time and repulse her for it, she may even more want to win back a portion of attention and love from you. You just need to love and give both the same attention, give them sincere unconditional love and not see the difference in children - this is the most important thing.
Never push your daughter away from you, think about how she could feel in those moments. Rather, it is the fear "I do not need, do not love me."
While the daughter is not, analyze what you do not like in those moments that are so annoying. Perhaps your aggression is associated with fatigue and postpartum anxiety, then you should rest. Play and walk with your daughters together. You can connect the eldest to the care of the younger one, but do not tell her the phrase “you are the eldest,” because she is also a child and also wants to feel loved.
Call, ask how she is doing, what he does. Tell me what you are waiting for and love her. When she arrives, together look at the children's photos, remember the pleasant moments of life.
I think having rested, you can establish a common language with your daughter. All the best!