Hi :)
I have M.E/CFS and I'm currently 32 weeks pregnant. It was a big decision to TTC for me and dh, as we both have the illness and we were concerned how we would manage with both the pregnancy, and a newborn baby.
Like you, I was on the pill for heavy/painful periods. I was very, very nervous about coming off it, as previously having a period would mean me needing to take time off work as the pain was just that bad. I made an appointment with the Dr and talked through my options. She gave me codeine for the pain, which I started taking from the day I was due on, even if the pain wasn't there yet (I also started to track my cycle in order to do this). She also gave me tranexamic acid for the bleeding, and there was another medication beginning with M (mefanamic acid perhaps?) that I tried which was amazing, but I was unfortunately allergic to it.
Luckily, the pain was never anywhere near as bad as it had been prior to me going on the pill. The dr said that maybe it was because I had been on the pill for so long or something, who knows. I did still get pains, but the medication helped to control it. So my best advice from that pov to you, would be to make an appointment with your Dr to discuss the best way forward really. (It then took us 18 months to concieve)
In terms of the M.E, the pregnancy has been really tough going if I'm honest with you. However, I believe I am in the minority, as many people notice reduced symptoms whilst pregnant. My issues were masked by severe sickness from 6 weeks, and then from 14 weeks I was exhausted. Not an M.E type exhausted though, this was something else entirely. My midwife/3 different Drs/consultant wouldn't listen to me - they just kept saying it was the M.E. After a huge battle, at 18 weeks I was diagnosed with anaemia, but then after even more battling, at around 26 weeks they realised my anaemia was actually really severe, as my ferritin level was only 6 (should be 70+). I believe had I not had M.E, they would have listened to my symptoms and what I was telling them, rather than just writing it off as M.E, if you see what I mean?
I guess the next part of our challenge is when we meet our baby in 8ish weeks time! I've gone on maternity leave early (at 31 weeks) as the M.E and anaemia have made it difficult, but that's by the by really. We have a lot of practical support from my side of the family. Only problem is they live 1 hour away, so we are going to stay there over the summer for 5ish weeks after the baby is born, just so we have a bit of extra support during the beginning whilst we're getting into a routine etc. I think that will help us both manage our M.E so much better.
Sorry, this has turned into a marathon post!! I just know what a strange time it is trying to decide whether to TTC with this illness, so thought I'd get out all of my experiences!! Good luck with whatever you decide to do.