Hi L....
There is a difference in speaking to your little baby girl in a mothering tone (psychologist actually call it "motherese") which is using high intonations and upward inflections, soft cooing sentences and this is encouraged for bonding and baby responsiveness... but, you're absolutely right about the baby talk hindering your daughter's speech. Baby talk gives the speech examples you really don’t want them mimicking (obviously). That’s like “tewwing youwr wittle sweethawrt she’s so cwute” – not a good idea.
I would start by repeating everything she says, or you think she's trying to say, in clearly annunciated words, point objects out while asking her 'what's that?' tell her and then ask her to say it, and of course, read read read to her everyday several times a day! :}
Baby signs is one great option for you to get to understand her better until she develops her verbal skills. Another great option is a speech therapist. If you live in the slc area, you might do well to contact 'The Children's Center' and a representative there can either direct you to the proper facility or help her there where they have two speech therapists on staff who i know of.
Good luck!