I <verb> and am <rest of sentence>
Since I'm a native Spanish speaker I tend to suppress the subject a lot when speaking, since most of the time it's tacit for us.
So, many times I find myself writing things like "but I'm not sure, and was wondering", which sounds good to me, but then I realize that, in this case, was doesn't have a corresponding subject, at least not an immediate one.
Can the subject (I) from the first part of the sentence be considered as the subject of the remaining statement ("was wondering")? I guess not, but it doesn't hurt to ask.