Sister, do not worry. They haven't officially denied you and are still investigating the evidence you have submitted. As a member mentioned its normal for them not to take passports at the interview, they still want to give you a chance to explain and answer any deficiencies that the interview and initial documents couldn't satisfy.
Your husband is right to suggest involving the MP. I would suggest you order ATIP GCMS notes to fully obtain information why the officer wasn't satisfied.
I would recommend you keep collecting proof between you two and your kid to enhance strong evidence before handing over to CIC ... if you guys haven't visited one another now would be the most ideal time ...