The first thing I would say is that severe period pain (which would be classed as pain that stops/hinders you doing day-to-day activities and/or that requires prescription-only medication) warrants further investigation to check that there isn’t an underlying causes, like endometriosis or PCOS. Many doctors will have you believe that this level of pain is ‘normal’, but the fact is that it isn’t. So if you haven’t already I would be asking your doctor to do some tests/refer you on (likely blood tests, a physical examination, and an internal ultrasound to begin with).
In terms of pain-management, I used to have extremely severe pain (as well as a myriad of other issues inc bowel pain) due to my endo. For me, the only thing that works is hormonal contraception; without it, I cannot function at all regardless of how many painkillers I take and how strong they are, or whatever else I do. That said, I did develop coping mechanisms, so my top tips would be:
Stick-on heat patches, or, even better, a heated TENS machine
Breathing exercises: I would find myself panting, so forced myself to steady my breathing, taking long, slow, deep breaths; it did help
Pushing: this will sound really weird, but my cramps were extremely strong, and spaced like contractions; I actually found pushing during them alleviated the pain and made the cramp/contraction more manageable
Pain-killers: I would use a paracetamol/codeine-based one along with a NSAID (like diclofenac); speak to your doctor for advice, but basically the aim is to take them regularly (at two hour intervals) to keep ‘topped up’. When I had chronic pain (caused by adhesions) I did this, and I had different types/strengths of painkillers that I used in different combinations depending on how severe the pain was. Also, make sure you take them BEFORE the pain starts (ie first thing in the morning), and take them exactly on time; do not take them late
Hormonal contraception: I know you have tried the pill, but I’m assuming you’ve only tried one type and brand from what you’ve said. Different pills work for different people, so this is something I would consider trying again. Ideally, I would look at cycling the combined pill (running packets together without a 7 day break), or trying the mini-pill (you may get irregular bleeding at first, but around 90% of women find their periods stop within 6 months of use); there are also numerous other methods inc the injection, Mirena IUS, etc.
Hope that helps, but please do insist on some tests if you haven’t already.