Deal with one issue at a time. First of all start with getting your pain identified/diagnosed.
It might be endo, it might mean tht the endo will make it nigh on impossible to naturally conceive, so that should be the first thing to do.
Keep a symptom diary. Where is the pin? how strong is it? how mny pin killers and what kind are you taking and how often?
How re your bowel movements? How much bleeding re you getting? Are you in lot of pain and/or bleeding when you ovulate? Can you feel the precise moment you ovulate?
how long hve you been trying for baby? Hve you managed to conceive before now but lost it? In other words does tht tell you that your tubes are probably clear.
Is sex painful? either during or after the event?
Is you pain throughout the month? generally all over the tummy region or site-specific.
You will probably need to hve a scan to check for ovarian cysts or endometriomas or rule them out, though not everyone with endo will hve cysts, and not everyone with cysts will hve endo.
You do need to try and find out wht's causing the pain. if it is endo then the only sure way to find out the extent of it and the likelyhood of being able to conceive without IVF is by hving lap op to check what's going on inside you, and how much the endo nd scar tissue are getting in the way of the ovaries and tubes to the uterus.
Meanwhile you don't have to be a martyr to the pain.Strong pain killers will not stay in you for very long at all. Take them if you need them while you are waiting for a diagnosis.
Once you know wht you are dealing with and want to try to concieve, by then hopefully if you do hve endo nd hve had surgery to clean you up inside, you might not need any strong pain relief for a good few months and it is the best time to try for a pregnancy then anyway.
Stressing yourself out doesn't help, so break it down in to dealing with one issue at a time, and first things first is finding out the cause of the pain and if that is going to affect your method of getting pregnant.
Best of Luck