How do I model a transfusion blood bag in Blender? I have been trying to model this asset for a few days but I cannot get it right.  


As everybody can see in the image above (thanks to Jachym Michal) for modeling this object I used an image reference and a grid. 
With my mesh as it is I have encontered with two mayor problems:


I have got the general shape down but with that messy topology I can't extrude it.
I have modeled the tubes of this thing (the cylindrical object that appear on the image) but I don't know how to joint it to the grid mesh.


For what I got it could be saved or should I start from scratch?

I hope that someone can help me out. 

Postdata: I have attached the blend file for anyone who wants it.
Here are some tips for modeling a very simple blood bag.

1) Use Subdivision modifier to get that smooth shape.
2) Use Mirror modifier for perfect symmetry.
3) Keep quads everywhere, so you can use loop cuts  



1) Inner and outer shape
- start with a simple plane and create the inner shape
- add loopcuts, move vertices.
- use Subdivision modifier to get the smooth shape.
- Use Mirror modifier for perfect symmetry and to save time.
  


use the same approach to create the outer shape  
make sure it connects nicely to the inner shape and there are no n-gons  





position some loopcuts for the tube openings.  




2) Add some thickness
We need some thickness to create tube openings.
You can add some loopcuts inside the edge to better support the geometry.


3) Create tube openings  (you can apply the Mirror modifier before that)
- add a circle and prepare an empty the loop on your bodybag (by removing the faces inside)
- connect through Edge > Bridge Edge loops.
- make sure that the number of vertices is the same. (8 in my case)
- If you want more vertices in your circle, just add more loopcuts.



Add some loopcuts for sharper edges.


Here is the file:


And the reference image I used: