I'm A 27 Year Old Female, Diabetes Runs In Both

I'm a 27 year old female, diabetes runs in both sides of my family, so I've always been nervous when I think I am having blood sugar problems. I have 2 children, last born in June 2015, and will be trying for a 3rd soon so I want to make sure I'm in good health before doing so (obgyn said its fine to start trying). I've been eating healthier for the past 7 months (lean meats, complex carbs, and lots of water), but lately I've been concious of portion control. I moved last year and have not been to a PCP yet, but plan to make an appointment with one this week to have bloodwork done since I have been experiencing a few things that scare me. My question is how extensive my blood work should be? I really just wanted to be tested for diabetes, because I've been having headaches lately, seeing spots (that go away when I eat something), and yesterday I got really nauseous after drinking sweet tea (I think the amount of sugar made me sick). The past two weeks I have been a little more physically active, and I'm still breastfeeding, so I'm not sure if that can contribute to any of the problems I'm having, especially if I'm watching portion control in what I'm eating.
Thank you for your help and advice!
K. Bride