I wanted to add that, with an overtired baby, I'm all for holding her for naps for a day so that she'll get "caught up." Sleep training is extremely difficult when a lo is overtired; at this point her getting the sleep is most important.
For the first 12 weeks, I always aim to do it "right"--going down independently, etc.--but if that doesn't work I'm all for the baby bjorn, swing, a walk, etc. so they don't get overtired. Stay focused on the goal, but realize that it may take a while to get there. You won't "ruin" all your work by being flexible occasionally so long as things don't become too habitual.
6 weeks is still very young and she may just need a bit more coddling--my little guy did. He's now progressing along through sleep training at 4 mo.
Let us know how things are progressing...