Kinda peeved at my OB

So I went to the ER for pain yesterday I'm 19weeks and 3days and they did a urine test and the ER Doc said that they found medium amount of bacteria. He told me that they did the test 2X to make sure it wasn't cross contaminated and sure enough i have bacteria. The reason why i am peeved at my OB because i saw her on Thursdays and she also does urine test and she said everything came back fine. And yet i have been having pains and here is the ER Doc saying they ran my urine 2X to make sure the results are correct and it is correct why didnt my OB on Thursday mention this bacteria that is a medium amount?? It should have been in my urine then like it is now. . Now i have to take antibiotics which im glad i found out now about the bacteria so i can treat it but wtf my OB should have seen this!