No one can make a diagnoses for you here, but make suggestions.
You should find a new doctor that will work with you.
If you have IBS, gas and bloating can happen because the large colon contract abnormally.
There are a specific cluster of symptoms for an IBS diangoses.
Do you have pain or discomfort?
Do you have altered stools?
Are you eating enough?
The stomach gurling is nothing to be concerned about. I'll post more on that later for you. It somewhat sounds also like your not eating enough in general.
Yeast is always in the gut and help protect you from pathogens. This is not likely your problem though, especially at your age.
Also on stress, it may not be how you think it works, for one the gas causes anxiety and the anxiety effects how the colon works.
I think its important to see another doctor. Self diagnoses is the leading cause of misdiagnoses. Also if you have IBS many homeopathic doctors do not understand IBS and IBS is extremely complex and an intereation between your gut and your brain. That does NOT mean its all in the head.
But this is VERY important.
IBS is one of the most common GI problem and at your age more likely. Not for sure because you have to have the cluster of symptoms minus red flag symptoms.
I am not a doctor. All information I present is for educational purposes only and should not be subsituted for the advise of a qualified health care provider.
Please make sure you have your symptoms diagnosed by a medical practitioner or a doctor.