3rd times the charm maybe? Clomid, confused, advice pls.

Hi ladies, im on my 3rd & possibly final round of Clomid 50mg, just losing all hope. Did anyone concieve on the 3rd round? One of the Dr's at the clinic told me if Clomid does work, its most likely to work withing the first 3 months, so she said after month 3 move on to injrctables. But then another Dr at the same clinic told me because my lining has been so good, i can do more rounds if i wanted to. So confused dont know what to do. Been TTC 13 months.