Six weeks is too young to be taken from Mama. I realize that's what we've always heard, "puppies are ready to go! 6 weeks old!" but after getting my holy terror Savannah Jane at 6 weeks I have come to agree with the folks here on DLC that it's too young.
I know you can't WAIT to have your baby at home... many breeders go all the way to 12 weeks with the dam, and most have moved the number to 8 weeks.
Off topic- if this is your first stubborn german dog (truth!), you may find it helpful to read Dachshunds for Dummies. I'm certainly not saying you are a dummy, I mean obviously not as you have chosen the most wonderful breed ever (even though they are poorly engineered)... but the book answers a lot of questions I didn't even know to ask. Well worth the investment.
Best of luck with your bundle of joy. Cutie for sure!