Hi cathy12.
First of all, what you are experiencing is not uncommon. Things should start to improve. I specialise in treating pregnancy-related pain and i see lots of women successfully go on to have multiple babies with "bad backs"
I think from reading your story that you haven't given us a "good" reason why it all started...was there an accident or incident causing problems? If there wasn't, then i would suggest that there is something in your habits that is causing a lot of stress on your lower back - it could be your posture, your sitting posture, your work might involve lots of bending over and you have a stressful way of bending over etc etc.
I think that is the issue that you need to sort out. You need to find out why your discs have suddenly decided to become painful (if they are the problem - it could be other things of course!)
If it helps you to know, i have helped lots of people simply by changing the pressure their spine is under simply by changing the way they do things. The way i see it is that you might see me for 30mins but you have to "live" without me for the rest of the 23hrs30mins i am not with you that day...and then the whole next day etc etc.
So it is vitally important that you attend to the way you do things.
A good physio should be able to look at the many different ways you move in your every day life and give you advice on how to change the way you move...
Now here is the best bit Your body will know if it is the right way to change! You should be stronger - get them to push on your outstretched arm in your usual posture and in the corrected posture - if there is nothing wrong with your arm, you will be strongest in the best posture! It will feel either "right" or "different" but not "painful".
I just saw a lady who for the last 4 years has been unable to touch her toes because of the pain in her back and legs. She sounds like she has the same problem as you...except she didn't have anything wrong on MRI! She couldn't bend, sit or even walk 100m without getting pain. We traced it back to a problem with her coordination of her ribs and the way she moves. She has spent thousands over the last 4 years. After just one session, she was able to go from being able to bend over to her knees only to touching her toes simply by changing the way she bent over! She is super keen and has decreased her pain more than 50%!
So there is hope for you Find out why your discs are under so much pressure and you will find out how to help yourself
Let me know if there is anything we can do to help more. If you are brave, post some video or photos of your posture and movements like bending over and sitting down and standing up from sitting and we can see how you are moving But only if you are happy for the world to see !!
Cheers!