Gestational diabetes tests confused

So im very familiar with testing my sugar. Ive had GD in the past. And I failed my test this pregnancy too. I am diet regulated for now. So every week I do a fasting blood draw and then eat and two hours later they do another blood draw. When i check it on my monitor its like 89-90. But my doctor will say its like 101. Several times what my monitor says doesnt match what they say. And ive even gotten a new monitor supplied by them. My numbers look good most of the time. But every week the numbers on my monitor don't come close to what they have. I get a little difference but why such a big gap? Is theirs more sensitive or something? I dont like my doctor she is rude so I dont want to ask her.