How Do You Know When?

I had to get off the depo shot due to severe pains i was having in my lower stomach. They said that is more than common for the depo shot to cause cysists on your ovaries, which is what i have. They suggested that i go off all birth control to keep the hormones out of my system to stop the growth of the cysists and there would be a 90% chance they will go aways on there own, so i would be able to avoid surgery. Well i have been off of Depo for one month as of the 17th of this month. I had bled on and off for a week or so before it was out of my system and since then just a week or so ago i thought i gotten my period but it only lasted heavily for two days then it was gone. Me and my boyfriend want another child sooner or later i was just wondering how do you know when you can concieve and how long does it take? what do you go off of when trying to plan when i dont have a period to know? My breasts have been very tender, i have been over emotional, cant seem to find any energy. Those seem like the symptoms of your period but i havent had one and i have been like this for two weeks atleast. Any advice or anything would be greatly appericated. Thankyou