Confused

I am a brittle type 1 diabetic and my Dr told me it would be "by a grace of God if I got pregnant" but I'm already 3 days late for my period and I have been feeling nautiouse, fatigued, emotional and have been haveing body pains and have been gaining weight. I took a test 5 days before my period and it was negative so how much longer should I wait to take another one? Anyone who give me advice would really be appreciated because I do want to be a mom and my finance wants to be a father 😊