Spanish term (edited): Me quede en segundo de comercio.

Or, perhaps, "business studies" (if she was attending a traditional university). There is no such thing as "commercial studies" in US English--and, as far as I know, not in any other variant of the language either.

The quality of the Spanish evident in the various postings from this text suggests that *university studies* are NOT being referenced here.

The general sense here is that she was in her second year of work toward her training/degree when she had to leave school to give birth to her daughter.

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Note added at 1 hr (2014-07-07 01:07:07 GMT)
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If the individual was enrolled in some kind of educational program within a correctional facility, then perhaps:

I was in my second year of study in a vocational program.