There are definitely things that are harder for BBW models, but you are basically describing the same problems ALL new models have. You are pigeon holing yourself if you think of yourself as *just* a BBW and not a new model!
You are 100% wrong when you say not many members prefer BBWs. There are SO many members on MFC, even if it's a small minority that prefers us that is still a huuuge pool of members. However - if you think "only BBW lovers will like me" you are closing yourself off to a bunch of members!
I have a lot of "BBW lover" type regulars for sure - but also just a lot of guys who like girls! I've been shocked when I see the girls that my regs like - my oldest regular is alo a regular of a girl who's like my opposite (very slim, super tattooed, dominant). Because he likes hot girls and the beauty of camming is that you don't have to commit to one person, you can enjoy all the ladies. My point being, it's not just guys who seek BBWs out that will be your regulars.
There are a lot of guys on MFC who will leave your room or never enter because you're a BBW. So, c'est la vie. You will get trolled more than thinner models (maybe?) - oh well. Just silently ban and ignore. There are SO MANY dudes who will love your body and your personality! So many!!!! So don't think of your body as a deterrent, it's a beautiful thing and it is a great selling point. I pinkie promise. I do believe it's harder for BBWs but it is what it is, you can take that as a challenge or an excuse!
My only other advice would be to investigate other sites - Clips4Sale is great for BBWs, so is Streamate because members can search specifically for that. I do know firsthand that you can make good money (at least, my idea of good money) on MFC as a BBW so don't self-defeat! Read all the threads for new models, absolutely get a better cam/Internet if you can, and be confident!