It sounds like you absolutely need new boots, but the comment about not wanting to seem better than you are...are you worried about over booting? If so, I don't think it is too much of an issue, you are working hard on progressing, you deserve a good boot and blade to progress in and keep you safe. I checked the stiffness on the boots you have, they are rated a 20 which, as you said, is beginner, pretty low support. Just for reference, I am also an adult beginner, not nearly as far along as you, but I am plus sized and opted for a pair with support level of about 80. Now my blades are beginner blades, but they are fine for my very basic two foot spins. I would definitely opt for a higher support boot if I were you, and I would check with your coach on the level blade (or maybe someone here has a recommendation on the blade type). Sounds like you are well past a beginner blade.