Art is often a struggle, and progressing can seem really slow and stressful. Sometimes it can feel like you aren’t getting anywhere, it’s hard, and I go through that a lot myself.
One of the benefits of keeping a sketchbook, is even if you are unhappy with your work, you can look back and see what you’ve learned.
If you feel stuck, you might need a mental break. If there are any figure/life drawing classes in your area, that would be beneficial to adding to your college portfolio. I know those classes can be hard to find, so even drawing family pets, or drawing friends and family even if they are simply resting or reading a book can help.
I like looking at animals and plants, sea creatures, birds, to get ideas for shapes and colors to use in drawing. Even just having a small bag of three or four different colored pencils, and ONLY using those for a day helps. Limiting what I have available, can force me to try new ways of drawing.
Don’t be too hard on yourself if it seems it is taking too long to see progress. Everyone learns at their own pace, the important part is too keep going. Draw everyday, practice, don’t be afraid of making mistakes. If there is something you don’t like about your drawing, keep going, because it means you see potential, it’s going to take a few tries until you figure it out. Once you do, that’s another tool in your arsenal you can use in the future.
Good luck, keep going!