Instagram is lowering your image quality because it uses a lot of compression algorithms in all uploaded photos. There are some ways to avoid it, check it out!
Here, you can find awesome tips on how to start photography on a budget with the best articles selected from MyOtherEye Blog. Check it out!
If you want to put a white background in your photos in the quickest way, you can use the Remove.bg website. Another way is to download the Background Eraser phone app, which is free but has less quality of the crop. The more professional way is by using Photoshop, however, it needs more time to complete the job.