Yes, and OP said their junior year math teacher caps the number of LoRs she writes each year and had reached that cap by the time OP asked. Queue Mwfan screaming.
Seriously tho, OP, you might communicate to the math teacher that McDonough requires a math teacher LoR (if you haven’t already). Have a brag sheet ready to give her. You might also get your HS counselor involved.