Quicker after one shot?

Charlotte
I've had one depo shot (at the time I didn't want to get pregnant ever again) and have since changed my mind and want to ttc again in a few months. Now I've heard all these horror stories of women ttc for years unsuccessfully due to having the depo, but I'm just wondering, is that because they were on it a long time? If I stick to the one shot would it be easier to get pregnant after? It would have been great if I had been smart enough to look this up BEFORE getting the shot lol!