Yiddish Dialects

Sholem! I'm completely new to this forum so sorry if I've posted in the wrong category or messed up somehow.

My question is on Yiddish dialects. The thing is that I'm very interested in learning Yiddish but it seems like there are multiple - very different - dialects. The study material I've used so has, for instance, claimed that there are three definite articles (that might change depending on the case of the noun to which it belongs) for all three genders: der/dem/dem (m.), di/di/der (f.), dos/dos/dem (n.). However, I talked to a native Yiddish speaker online a couple of days ago and he told me that the only definite article in Yiddish is de/di (depending on the pronunciation). As a matter of fact, it seems that a lot of what I have learned using my study books is very different from how Yiddish is actually spoken.

Could anyone please tell me why it seems that my study material is so different from actual Yiddish? Is it just because the native speaker I talked to speaks a different dialect (he is a Hasidic Jew living in NYC) or is my study material archaic (I wouldn't think so since everything I've read so far has been in accordance with other resources)?

Another example: In my textbook it says that "I put the potatoes in the oven an hour ago" is "Ikh hob geshtelt di bulbes in oyvn mit a sho tsurik" in Yiddish (if I remember correctly; there might have been a definite article preceding "oyvn"), but the native speakers disagrees and says that isn't how he would say it in Yiddish. He'd say, and I'm quoting his message: "Ikh hub gelaigt de kartoffeln in de oyven a shoo tzerik".

This whole thing has gotten me quite confused and I am now insecure with regards to what dialect to study - any help clarifying this mess would be greatly appreciated - a sheynem dank in advance!