You may have to do a little math here, but what you should know is that as far as being away from the US, since you were never gone longer than 6 months, your "continuous residency" is intact, and you have not been considered to have abandoned your residency.
As far as applying for your citizenship, your "physical presence" in the US needs to total 4 years and 1 day in order for your citizenship to be approved. That's where the math comes in: you'll need to calculate how much time you spent in the US over the last 7 years, and as long as they total 4 years and 1 day, you'll be fine. (If you do not meet the total, then you'll need to make up that time and then apply).
As far as not having worked in the US, you'll just need to answer accordingly in the Form N-400 that you have not filed income tax returns. If you're asked about this in your interview or at any other time, you'll need to explain that the reason for not filing is because you have not been working and have no income to report.
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