Serious question for third trimester moms. TMI

Sophie
Okay so I've been reading and it says that during the third trimester it's normal to have diarrhea. I get that. My question is. How much diarrhea in one day is considered normal ? I have diarrhea literally as soon as I've eaten something. 5-10 min and it all comes out. Whether I eat just a yogurt or an actual meal sometimes even just water. It all comes out. I'm tired of asking my doctor cause she always brushes everything off as "it's normal". I've gotten to a point where I don't even wanna tell her any odd symptoms or concerns anymore cause she makes me feel like I'm just exaggerating and complaining when in reality i just need her to know that I have certain things. I'm
33 weeks on Monday and I'm feeling so weak and drained cause I guess my body doesn't even have a chance to grab any nutrients from food cause it all just comes out. My weight has been dropping slowly for the past three weeks. Which again I have read is normal but I'm wondering how does my baby grow and get anything she needs to grow healthy. Again my doctor just said it's good cause I'm too fat. So back to the diarrhea question. How much is normal? Today I've had it like 5 times already and I can feel it's not done yet. I'm miserable. Please anyone who went through this and can explain it?