Help an Aspiring Photographer to get better pictures

Hello everyone! My name is Theodora and i'm an aspiring photographer! My goal is to raise enough funds so that I can get a Nikon AF-S NIKKOR 80 - 400 mm f/4.5-5.6G ED VR Lens! I currently have a 70 - 300 mm lens (borrowed from a kind friend) which I use for wildlife photography of birds, but unfortunately the photos which I take are missing a lot of detail, and close up shots of birds 100m away end up disappointing and noisy even after editing. You can find me on Instagram at @mudpiedunicorns to see some of the photos I've taken (: It would really mean a lot to me if I can get an upgrade. I am currently an undergraduate student in Singapore studying environmental studies.