Your ingredients ratios are on point, same as I use. Be careful not to over-proof, it causes deflation. Also, you might not be kneading quite enough. I ran into these issues myself on my quest for the perfect homemade bagels.

Knead 15 minutes and proof at room temp (70° F) for 1 hour. Portion into nice rubbery balls and pinch them into rings. I find this technique easier with a drier dough. Let rest 10 minutes then stretch them a bit. At this point you could either put them in an airtight container in the fridge over-night, remove and go straight into the water bath. I do 20 seconds on each side otherwise they get too tough and also might deflate. I always leave overnight for morning bagels. Or you could leave on the counter to raise just a bit then into the bath. If left out on the counter for second raise, only let raise to 3/4 of full raise, otherwise they will deflate from the bath. I personally find they are more forgiving if left overnight in the fridge. In either case, after the bath they should go straight into a preheated oven.