as I understand the Texas state government...

Texans do not have the right to propose amendments to the Texas state constitution that are simply placed on the election ballot and voted on by popular vote. In Texas, amendments to the State Constitution can only be proposed by the State Legislature.

So in that sense, we as citizens cannot gather enough signatures to get an amendment on the ballot. It has to come directly from the State Legislature.

Is that correct?

I think it is, which means that Texas is not going to get recreational weed anytime soon.

Ballotpedia forms of direct democracy