Post-treatment fertility

Hi.
I am looking for some information on accessing fertility assessments.
I had lymphoma 4 years ago and was treated with chemotherapy. Before treatment, I was counselled on the potential effects of the prescribed chemo (ABVD) which I was reassured would have a very low risk of damaging my fertility, and so I opted out of fertility preservation treatment at the time as I was only 26 and felt I'd rather just get on with my treatment. However, due to an adverse reaction after the first round, I was very quickly switched onto GemCis chemo, I now know is much worse for fertility. I was not advised of this potential side effect being so much higher risk at the time, which I am quite angry about now.
I'm 30 now and I am hoping to start a family in the next few years, and I am seeking some reassurance on how badly my ovarian reserve has been affected by the chemo. I tried to request AMH testing or antral follicle counts from both my GP and my private health insurance (AXA) and it was declined on the grounds that I had not been trying to concieve for >2 years, even though I provided my cancer history to them. Ive read elsewhere that this should not be the case for cancer survivors given the known impact on our fertility, so I am struggling to understand how to get my concerns "heard". It is a HUGE source of anxiety right now for me because if I found out now that I'm actually the equivalent of e.g., a 38 year old, we would try and have children sooner, but ideally we are hoping to wait a little while longer. But I am absolutely terrified that in 2 years I will find out that it is too late and I've missed my chance to have children, it would absolutely break my heart. I don't understand why none of my healthcare providers are able to do anything about this.
So, long story short I am trying to find out if there is a specific way to access these tests where I wont keep being told that I am being ridiculous for worrying about it at the age of 30 when I am not yet trying for children (a direct quote from my GP...). 
Thanks in advance for any advice!