Wait! Every two weeks is nothing to worry about, and 3-4 weeks is hardly a long time. Double check the conditions that she is under and be patient. Stop trying to adjust your snake to fit your schedule. If she only wants to eat every two weeks, then let her. She WILL eat again, and again. Worry after three months or if you start to see weight loss. Here are some tips to get her regular:
Don't provide too much space. They can get lost in there and never even find the food (by cruising the perimeter and not exploring the center).
Lower traffic around enclosure. People and pets constantly walking by can stress them. Cover with a towel if you can't relocate.
Make sure your heat is right.
Feed shortly after dark (or lights out). They are nocturnal, after all.
Watch for caudal luring. This could signal hunger (or just entertain you). Provide substrate that can be burrowed in like shavings care fresh etc...
Try a smaller item; maybe one that moves less (thumped).
Reduce handling, and don't handle for two days before feeding.
Be patient and persistent (like you have been). This is normal for some dums especially in the winter.
Good luck,

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Zoodude
"Just because I'm paranoid, it doesn't mean they aren't after me."