I'm so sorry you are going through this, indiegirl. I wanted to chime in and let you know my experience.
I am hearing impaired - I was probably born with the loss. But it was not discovered until I was in kindergarten and was given a hearing test along with all of my classmates. And my mom is the best!
So please don't beat yourself up about this! My grandmother was just about to say something to my mom when I was given the hearing test - since my loss is relatively mild, it was pretty sneaky. I consider being hearing impaired to be one of the "invisible" disabilities. No one can tell by looking at me or even by superficial interaction. But sooner or later someone will notice something "weird" or will wonder where my accent hails from. I wore hearing aids until I became too self-conscious (early adolescence) - I am considering getting another pair now that new technology means smaller aids with less annoying feedback, etc.
I don't know that I was behind in my speech - but if V has some mild hearing loss, it seems like it would fit with her expression and understanding being a bit behind. If you don't hear a lot of general conversation, then it means that you don't pick up as much as other kids. Also, from personal experience I usually need to "tune out" background noise and chatter because I find it to be very distracting. I work too hard at trying to understand the flow of conversation and at trying to fit in blank words or phrases that I missed. So I just tune out and it can sometimes take a bit more than usual to get my attention - more than is explainable by the amount of impairment I have. Does that make sense?
Anyway, I truly hope you don't need to deal with any congenital issues. Hopefully it is just fluid build up and she will catch up so fast your head will spin! Also, I really liked my speech therapists! They were great!
Good luck and keep us posted!