Chance of having multiple pregnancy??

H P

Hello all, so after ttc 6 months with no luck my Dr put me on letrozole 5mg. Total 6 follicles finds on cd11 sizes 21,12,8mm in right ovary and 18,20,9mm in left ovary same day giving trigger shot after on cd13 I am ovulate. Having natural sex not iui. Now I am concerned about having multiple pregnancy. What are the chance of having multiple pregnancy with 3 mature and 3 immature follicles??