Hi jhs and welcome to the forum
It is always harder to predict the income of self-employed traders, because you never know exactly who is going to turn up and spend in your shop on a day to day basis.
If you are trading at a loss, and having to rely on monies from third parties just to keep afloat, this may be a message to you that the business cannot support the IVA. Would it be more sensible to cease trading and try to find salaried positions?
One thing you must not do during an IVA is to incur additional credit which you cannot afford to pay, or fail to pay your income taxes on time.
Your IP might be prepared to agree to a reduction in payments, which may need the sanction of your creditors, however this could be just delaying the inevitable if the business in in trouble.
Regards, Melanie Giles, Insolvency Practitioner