how to vary child maintenance from consent order?

Any advice appreciated please to following query!
I divorced a year ago after a very acrimonious drag through all the courts. I have joint residence of our 3 kids and they spend about 45% of time with me.
In Consent Order, relating to split of financial assets I agreed to child maintenance of a fixed ammount per child until they reach 18. However, to add to my problems, I have recently lost my job and my financial situation has dramatically changed. I remember my barrister saying the court had no authority to enforce child maintenance and what I agreed to in the consent order would only hold for one year at which point I could apply for CSA levels of child support. I do not want to go back through my sols etc as it was so expensive (and they have a habit of giving endless caveats and expanding simple issues!). Questions are as follows -
1. Is this correct, ie can I vary the maintenance level agreed in a consent order after 1 year?
2. What is the procedure?
3. When calculating income, is this taxable income as per my tax return, ie does it include investments, savings etc?
4. Are any pension contributions I have made this last year also included?
5. Where do I go to find out answers to above and similar questions? I have heard CSA is pretty hopeless.
6. Is it relevant that my ex is now earning more than me? Seems a tad unfair to be paying her such an ammount when she has kids 55% of time and got 50% of all assets and is living with a partner who is also employed (basically I feel like I am paying her holiday money).
Thanks!

If you go through the CSA, they will look at how often you have the kids, and how much you earn. They don't look at how much your ex earns though.
secureonline.dwp.gov.uk/csa/v2/en/calculate-maintenance.asp
that is the CSA maintenance calculator. Put it your details and it should give you a rough example of how much you will be expected to pay, if you go through them.

I'm not sure how it would work about your contact order though. I should think though, that if your circumstances have changed, you can change the amount you pay. I'm not 100% sure though, sorry.