It’s not just you that will look flaky, but also your HS as a whole if you back out of ED. You, your parents, and your guidance counselor sign that you understand ED is binding.
Talk to you parents to see if you can afford your ED school. If the answer is ‘no’ after running the NPC, do not apply there or to any other school that you can’t afford. It’s a recipe for heartache in the spring if you have acceptances to dream schools that you have no way to pay for.