What's wrong with this sweep?

I'm not sure if I understood what you did in your model, but I tried here to show you how to do that sweep. I hope it will help you. Have a luck with a rest of your model. And, in my opinion, It is better to make mouse using some surface tools.

  1. Step 1:

    This is a profile sketch

  2. Step 2:

    This is guide curve. Also, I think, it is better to make just one side of guide curve because this model is symmetrical, but I made this by mirror tool, to be more like yours

  3. Step 3:

    Another guide curve

  4. Step 4:

    This is a path for sweep

  5. Step 5:

    This is a sweep

  6. Step 6:

    If you are not satisfied with your sweep result, but one side of your model looks good (for example, right side of your model), you can do "Cut with Surface" to cut deform side of the part. This is possible to do because your model is symmetrical.

  7. Step 7:

    This is a result of the SurfaceCut

  8. Step 8:

    Now use Mirror tool to mirror this body. Make sure that you Merge result to have one single body, and make sure you mirror body not feature(this is really important)!