Endometriosis suspected but not confirmed. Should I still go for infertility treatment?

Testing First. You need testing but not treatment just yet. Endometriosis is associated with infertility but these days we do not need to confirm the diagnosis to treat. We do need to determine the egg quality, sperm quality, tube status, and uterine cavity status. We can then begin to determine your treatment options. You can have just as good a chance as anyone in most cases. Best wishes.
If not conceiving .. If you're not conceving easily (after a year of trying if under 35, or after 6 months of trying if 35 or over) go ahead with fertility treatment. If endometriosis is suspected but not confirmed and you're trying to conceive a laparoscopy to 'prove' you have endometriosis may not help your fertility much, and treatment of endometriosis on your ovaries can lower your egg supply. Talk to your md.
No. The cause of endometriosis is unknown. The model describing endometrial implants is an unproven theory. Once the diagnosis has been made, invasive treatments are often undertaken based on speculation and this model. Invasive treatments can evoke fertilization-impeding adhesions. Women with endometriosis have dysparunia, which might limit sexual activity and potential fertilization events.