Toddler drinking lots and not eating much

[SilverLining17]

My dd is 19 months. There is a strong family history of type 1 diabetes. Lately whenever she finishes her drink she says more juice or more milk but she doesn't get upset if I don't get her any more. I'm not sure if she just didn't have the words before so didn't say it?
She doesn't eat that much but has always had a lot of milk. She hasn't lost weight but does seem tired. I've checked her wee a few times and it's even negative so far but I don't know whether I should do a blood test as well?
Today she has has had 14oz of milk (which she always has had) and some water but hasn't eaten much.
She was also drinking the bath water the other night but I don't know if that was because she was pretending to make tea with her cups. She doesn't clammour for other people's drinks or anything.

Should I try and get a blood test too?

Hmmm, so average 19 monther weighs about 10 - 12 kg, so advised total fluid intake per day (pauses for maths) would be about 1 - 1.1 litres per day...which is about 33 - 37 oz a day (though can get a few oz through food). So far, from your description, doesn't seem to be drinking excessively?