You are not fair, Saif. Erik and me have spend a lot of time to find the mistake in your application and to give you hints to solve your problem. Up to this moment it's my strong belief, that you are really doing something wrong, when trying to derive a feedback from a winding, which does not see the load changes. And if you had a bit knowledge on transformers, then you would realize that my arguments are true and you would not think to get the thing to work anyhow.

Erik told you, that this application also highly depends on used transformer. It's not so much a question of what shape the transformer is (EI core or what else) but how high the magnetic coupling (stiffness of transformer, depending on core material, etc.) and impedance of secondary windings is. You can succeed or fail with the same identical circuit but using two different transformers. Choosing the right transformer is THE key issue here!!

Nobody is teasing you, because you don't have a scope. But keep in mind, that you design a circuit which handles dangerous voltages. And if you make something wrong, then your circuit can produce dangerous high voltage spikes, which can hurt or even kill people! To be told by two independent professionals, who earn their money since decades with doing in electronics, that 'working' without a scope is not a good idea at all, is not 'teasing' you, but informing you that you are on the wrong way! This is not a question of resources or money, but how to manage a project.

There are some DIY sites in the web, which tell you how to build a simple storage scope, which would allow you to have a look at your signals. Costs are absolutely minimal and no exotic parts are used.
The problem is not, that you don't have the resources, but that you think you do not need them, that you think you can manage such a dangerous project by simply blindly guessing, which is what you do, when working without a scope!

Kai