Plus you are 30 weeks pregnant. The most harmful effects of any medication is during the first trimester when all organ systems are developing and developing so rapidly.
Pretty sure the recommended dosage on the side of the bottle is 2 tylenol every 4 hours as needed. No more than 8 per day. So yes, you took way too much. Definitely don't do that again, but your baby will likely be fine.
I wouldn't panic. As it had been said you do want to be cautious with any meds during pregnancy. However Tylenol is one of the safest painkillers to take during pregnancy just follow recommended dosage. It's unlikely that you caused any harm to your baby. As for research, due to the unethical nature of doing research on pregnant women, there is limited research on effects of some drugs on pregnant women so don't panic because Tylenol is recommended over aspirin/ibuprofen when pregnant.
Taking anything during pregnancy can be harmful. Tylenol has been tested and causes less than some other options. Through out my pregnancy I've been prescribed several medicines that can have side affects the risk is lower than the complications I've had. Just be cautious of any medication any if it can cause issues. It's not likely if you have only taken it a few times versus everyday. I wouldn't worry too much if you are you can ask your doctor.
According to this link, you took twice the recommended amount two days in a row.
Although you took way too much, it seems like if this is truthfully the only time you took meds, your baby is unlikely to suffer harm.
Really though, it would help to pay attention to drug dosage warnings.