4w pregnant and got pfizer booster last few days

Sayang, this is something you really need to discuss with your doctor or OB-GYN as soon as possible, don't worry, but do get their reassurance quickly since it's a timing thing they need to know about. A few of my mum friends who got vaccinated around their pregnancy were also worried at first, but their doctors helped them understand what happened and they all ended up fine, your doctor will have the best information for YOUR situation. Just make that appointment soon, okay?