When meditating, it's a lot like dreaming while awake. It can open us up to what is most commonly known as "visions" and that's exactly what you are seeing. Sometimes they mean nothing, othertimes they have great significance. As you grow and develop spiritually, you will be able to tell what is unusual. Everything has some form of significance however, because as we quiet our minds we get to see what was hiding in their all along. That thing we call "intuition" becomes louder. So this doesn't mean a spirit is necessarily "giving" you these images but more likely that they represent something to you that reflects your current situation, just like your dreams would. But unlike dreams, we can meditate any time we wish and we can consciously sort out the garbage from the diamonds.
You are asking those on the outside what you have experienced within. But within is seen from your perspective, your reality only, therefore it mirrors your mentality. You need to ask yourself what it means. You need to reflect on these images as they are happening and follow your gut feelings about it. Be confidant in what you think because you're the best judge of your own mind.
Even if, let's say, your visions were actually your clairvoyancy seeing that which is around you. It would still be colored by the lens of your perception! Your mind must still process it in a way you can comprehend. Our minds MUST know. They must have an answer. It's ingrained in the programming! So it gives us an answer whether we realize it or not. Sometimes that makes it a bit different than the original, but until you can open your mind up to any possiblity, and be able to say "I don't know and that's okay" confidently, you'll always have that lens. So while you may see a white bird, someone else would see a different image that represents the same main idea. And that even goes for the appearance of spirits and traveling the other worlds.