Filing taxes joint or separately?

Ok I'm so confused. Id appreciate anyone's input. So my husband and i goy married Jan 20, 2017 we had our 1st baby in July of 2017 so we filed married joint. But we onky got back $3,000. We used daycare taxes, claimed our baby and claimed my grandmother. I was kinda sad because I always hear alot of people getting back way more. So now this year I was thinking if i file married separately maybe i can get back more money? Idk I'm lost here.