My daughter is 19months and is constantly drooling. I think it's just from teething as we are awaiting her two year molars. Could it be something else?

It could be. It could be due to teething. At ths age your chid should be gettig her 1st molars in. In some cases it may even be her 2nd molars coming in a little early. As long as she has no other symptoms i woldnt worry about the drooling.
Yes. It can always be something else, from mouth sores, to sore throat, to muscular problems in the mouth, to many more. But i agree with you, teething seems to be the most likely cause. If additional symptoms develop, then i would have her checked by her health care provider.
Yes. Drooling could be caused by teething but it could also be other pathology's or conditions. You may want to go to the doctors to determine what the cause of the drooling is.