If you say that God has communicated with you, this implies you've figured out how to tell whether something is a communication from God. So how do you tell?
Very good question. Different Christians have different spiritual gifts. Mine seems to be the "word of knowledge". I receive on occasion clear direction accompanied by divine knowledge (not the only example of communications from God, but an okay one, to start).
Let me give you two little examples of this in operation:
*A friend who is not charismatically-minded became more open to gifts of the Spirit while at a small conference. Sitting for lunch opposite a stranger, a pastor from another city, he felt a strong urge he went with to blurt out, "You need to stop cheating on your spouse, Pastor!" and the pastor left the table and ran from the room (and the conference) to return home promptly! This friend is big on strong relationships and in ordinary circumstances would be hesitant to talk to a pastor he personally knew if he had confirmation about marital infidelity.
*I'll be witnessing to someone in person, where my warmth and genuineness (as they do for all of us) comes over much better in person than online. I'm being exceptionally patient, gentle and Spirit-filled with a young man who is being hostile. As I listen to the man, I silently ask God if He has anything He needs me to know or do in this situation, and an inner voice tells me, "His father has cancer."
Not wanting to blurt out as in case 1 above (from experience!) I take a different tack soon after and ask the man, "Tell me about your home life, if you don't mind. Are you in a good situation with your family?"
"Yes, sure," comes the reply.
"What about your mother?" I ask.
"She's great. A good mom, I love her," he says.
"And your father?" I ask.
The young man starts crying, sobbing. His dad has terminal cancer. I explain the power of Jesus Christ as healer and ask if I might have the privilege to pray for his father. Sometime later, we end with an embrace as he departs. A weight has fallen from his shoulders and he leaves, promising to do as I request and read the gospel of John, prayerfully.
Now, being rationally minded, as you are, I must consider several plausible alternatives:
1) Coincidence - difficult to write these things off as anecdotal coincidences, since I have had words like this or prophecy that has come to pass often enough to be statistically improbably.
2) Self-delusion - difficult to swallow, as whenever I get that prompting or nudge and sense it is God talking/moving, my knowledge is complete, accurate. I've never said to someone, "You mom is very ill!" when it was their uncle or no one who was ill--it was mom. These words are 100% on par.
3) Reality - Words of knowledge never come to me about friends and close ones, but only strangers. They can be used for reproof or to heal or edify. They seem to align with the nature of spiritual gifts--a "special" Word of Knowledge.
4) Proximity - They fit timespace and a need--they've come when I am threatened with hostilities from someone I'm trying to reach out to in love, they mostly come when I'm in the room or locality of the other person or persons.
It has happened online, though. I've told an atheist online, "God truly does wish to touch base with you. Tuesday, 8 PM, I believe," and I got a note online Wednesday:
"I got a phone call a few minutes before 8 o'clock last night that my grandma died. Say something stupid and I will @#$@% kill you!"
"I'm sorry for your loss. My thoughts are with you at this difficult time for you and your family," I replied.
"That's big of you, thanks. I appreciate it." came the reply.
You should imagine by this point that I was tempted to inquire after this atheist's grandmother's mode of life. A dollar says she was a good Christian woman who talked with her grandson about repenting of atheism...