Hi , I first would like to officially welcome you to the community! It is great that you have already jumped in to connect w/our members by asking this question.
Secondly, I am truly sorry that you are not getting answers to the concerning pain that you are experiencing. Kudos to you however for being so very proactive in your health & continuing to get to the root cause.
While we cannot provide you with medical advice as we are not qualified healthcare professionals, I can share that endo may cause bladder & bowel pain/issues. Let me share some resources with you.
https://endometriosis.net/clinical/dealing-complications/
https://endometriosis.net/symptoms/bowel-bladder-problem/
A Laparoscopy is considered the "gold standard" to obtaining an official diagnosis, which of course I can understand is a lot to consider. You can read more about that here. Have any of your doctors discussed exploring dietary changes prior to a lap? For many women living w/endo, diet plays a big role and can help to ease pain, symptoms & bloating. This article may help if you'd like to check it out here.
Finally, while having a heavy period is a common symptom of endo, it is not the case for all women.
I understand I have shared quite a few resources with you, but hopefully others from the community will be along to share their personal feedback & experiences as well. Personally for me, when I was first diagnosed with endo, I did not experience any bowel pain, but too began experiencing sudden pain about two years ago. Certainly very frustrating & painful, but thankfully for me...the pain has decreased a bit just over these past few months. Fingers crossed I stay on that path.
Will you do us a favor & keep us posted & let us know how things progress? Know we are always here...reach out anytime!