Yes endometriosis can be (and in my case) is on my sciatic nerve and some nerves in my lower back and going down into my legs - so I have lots of issues standing and walking for a while and sometimes randoms spasms there as well.
I'd ask for the notes from your precious surgery - as endometriosis tissue can be on the bowels and bladder (mine also is), and it may have led to your previous issues (not 109% but seems like it). I'd ask gynaecology or your GP for a referral to colorectal surgery and/or uro-gynaecologist. Look into antispasmodic medication, Anti-motility agents (e.g. loperamide/Imodium) as well - ask your GP and/or colorectal surgery for this and what they think you should start for your bowel issues.
They should be looking to remove both the cyst and firboid as soon as possible - and biopsy them. If they think you have adenomyosis - ask about getting the mirena coil inserted at the same time and also perhaps a uterine ablation (look into this to see if you want this). It's very good you're getting on the waiting list for a diagnostic laparoscopy, also ask for when they find the tissue for excision surgery and ask for that to be on the bowels as well and for colorectal surgery to be on call to come and excise that tissue. I have a cysts currently as well, however I haven't had it removed yet (on the list and have an appointment with my consultant on Friday about this), and I'm on the list for an excision surgery of everything on my bowels, bladder (as much as possible with urology and colorectal as well), not sure about the nerves in my back yet - I'm going to see with ortho for issues with my back and after I meet with my consultant well see if we need something checked with my nerves first by neuro potentially or not. I'm going to try with my pain consultant/palliative care to see about doing sacral nerve stimulation (but I'm not sure yet and they haven't decided whether to put me forward yet).
For me excision has helped for the first few months to a year after but my tissue grows back rapidly, there's also recovery from surgery and then also adenomyosis which for me hasn't resolved from the mirena and tranexamic helps with my heavy bleeding and leaking but not anything else. As adenomyosis tissue cannot be excised, it continues after the surgery anyways - that's why I'm thinking of doing a uterine ablation and perhaps a hysterectomy as well (I don't want children). After the excision surgery, you also have more adhesions grow, the scar tissue forms and also on my bowels, bladder and back - not all of it can be removed due to the position and amount. I may for my next surgery have more removed but this comes with side effects on my bowels (perhaps a stomach and other issues), for my bladder - I'm not sure what else can be done, unless I'm willing to go for something more like removing it and having a bag there as well (big decision and risk, so I don't want to do that right now). For my back and nerves, I'm going to see what ortho and my gynaecology consultant suggests and perhaps neuro as well. I'm aiming for the sacral nerve stimulation now for that anyways with my pain consultant/palliative care.
I am glad the information is helpful, the links are also really good. I just know that I had to learn a lot slowly and would have liked to know it all from the start, so I hope it's not too overwhelming as diagnosis can be when you're not expecting it at all.
Go to your GP about trying naproxen and/or mefenamic acid, perhaps opiods (depending on how severe your pain is, perhaps temporarily for flares? first, rather than going long-term for the sake of it).
You can look into stopping your period, but as your's isn't heavy, it might not be needed. If you want you can get tranexamic acid for a heavy period. I'd still try the mirena coil for adenomyosis as it will thin your uterine lining and cause less cramps in general. If insertion is your fear (either get them to do it in surgery - only issue is it could be a while away) or make sure the GP gives you the pain relief (Licodaine injection, numbing sprey/gel, paracetamol and ibuprofen 1 hour before etc).