Can tipped uterus make it more diffucult to become pregnant?

On its own, no: The concept of a "tipped uterus" being associated with infertility is not due to the position of the uterus. With severe endometriosis, the uterus can become fixed in the same position. This is due to scarring from the endomertiosis, not just because the uterus is "tipped".

Depends.: Depends on your definition and etiology of "tipped". If you have a congenital uterine (mullerian) anomaly your fertility is undoubtedly decreased (septate, arcuate, bicornuate, didelphic uterus). If you are talking about an extremely anteverted/anteflexed or retroverted/retroflexed uterus, this can also decrease your fertility especially if associated with endometriosis or pelvic adhesive disease.