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The criteria to conceive are:-regular periods;proper ovulation;normal semen analysis
and patent fallopian tubes ;if these are proper you can conceive.The problem with you may be due to endometrosis and now the chocolate cyst
for which you are supposed to have surgery.After surgery you can have natural conception but the time when you will conceive cannot be said and if it happens that you do not conceive there is presently no time to wait and you have to go for IVF as it is the better option.Please understand that IVF is better because you should get pregnant soon and have a baby and the reason for IVF is that age is running out and conception in later part of life(40 or more) is complicated and there are chances that the baby may suffer congenital anomalies which is common at later age so your doctor has advised you for IVF.Please follow the doctor.
All the best.