Oil will typically stay in the stomach for many hours so your issue is pretty normal. Doing a flush with undigested food still in the stomach does not work so well. Better to do it on an empty stomach if you can. It will typically take many flushes to get the GB working the way it's supposed to so patience is key. I had to do 6-7 Liver Flushes before I could feel my GB working right after a meal.

Maybe do some colon cleansing before the next flush as well to make sure the intestines are clear.

I suffered from the same condition. You need to start with SCD diet and proper food combination that will be easy for digestion. Also supplement with digestive enzymes to support the digestion track.

Here is a resource on SCD diet: http://www.scdlifestyle.com. This will tell you what to eat. You can also try khichadi, an Indian dish which is very easy on the stomach. Make the non-spicy, non-fat version.

This will tell you how to combine food for better digestion.
http://www.drkaslow.com/html/food_combining.html

Try now foods super enzymes as they have pancreatic enzymes as well as ox bile. This will help in digestion of carbs, proteins as well as fats.

You might also be deficient in stomach acid. Have you been on PPI, antacids? Or may be a H. pylori infection?

You have to liver flush. I was scared of doing the Liver Flush too. So I got an ultrasound to see if I had gallbladder stones or if my liver and gallbladder were inflamed. Everything was normal so I proceeded to the liver flush. If you are too afraid to drink half cup of olive oil then you should try 1/4th cup or even 1/6th cup. But get started with the liver flushes.