Not sure how to answer your first question, but regarding fundal height ...my doctor told me that as long as the measurement is whatever week your in, plus or minus two weeks, that the baby is growing fine. For instance, when I went in on Monday, I was 28 weeks, but my fundal height measured 29 cm. So it was within that +/- 2!
Well I know that each ultrasound the measurements could be either further along or behind, but that's because the ultrasounds are truly just an estimate. Plus, I don't know what the Fund.ht stands for, so that may not even be the measurements. As far as the bicornuate uterus, I know a little about this situation but only the risks during pregnancy if you are diagnosed with one. I would talk with your doctor more about your concerns, because the risk of miscarrying is higher with a bicornuate uterus - as well as pre-term labor and abnormalties. I'm not trying to scare you or say this is your situation, but I would be contact regularly with your doctor regarding this situation - truly only they know what is going on with your body.