Got an RFE, do I need a joint sponsor?

[MvS26 0]

A little background about myself:

My now wife(USC) and I have been living together in the Netherlands for 3 years and decided to move to the US because she got a great job offer. She moved to the US in august 2016, we filed our K1 and I was approved in February 2017.I moved to the USA in March and got married to my wife in March as well. We filed for AOS, EAD and AP in April.

 

We got a request for initial evidence (I-485) stating that my wife needs to submit supporting tax documentation for the most recent tax year (2016). We submitted W2's, 1099 and 1040 in april but maybe we missed a form, we also submitted a letter of her employer as well as all the paystubs she had. Her income is above the 125% poverty line, but because she only started working in September 2016 her taxable income of 2016 is below the 125% poverty line. Now here is my question: We requested an IRS transcript, is that enough evidence for the RFE or do we need to get a joint sponsor because her 2016 income is below the poverty line? I rather not get on because my wife technically makes enough money.