Refusing blood work

Can a mother get in trouble for refusing to get certain blood work done during pregnancy? I have hypothyroidism and I honestly feel like my doctors just are not listening to me. I throw up every single time I take my medicine in the morning so they just keep raising the dosage. I'm now up to over 200 micrograms which means I'm having to take 2 pills because the medicine doesn't even go that high. I'm honestly just over being ignored and I know this dosage is to high so I have refused to take it and was just wondering if I was allowed to deny them to do anymore blood work concerning my thyroid levels.