You are probably okay, but there can be a few dangers.
Let me start off with a personal story. I had a friend who was a very fine guy; but he wound up in a mental institution. Most people can practice yoga or meditation without harm, but there are hidden dangers.
Jesus' commandment was to seek first the kingdom and all the other things will be added. He also stressed the need to have a pure heart.
The hidden danger with yoga or meditation is that one can raise the kundalini energy prematurely -- before being ready to handle it. It can enter the heart chakra and then the heart corrupts that energy in ways that may not be apparent to the person himself.
It is more dangerous to try to raise the kundalini up to the inner eye chakra via meditation or yoga. Jesus mentioned that chakra too, calling it the "single eye." If that single eye is pure and in light, it's wonderful to have the kundalini reach it; indeed miracles can be performed that way. But if the inner eye has a slight impurity or darkness and kundalini enters, it can exit, going out into the world -- and that can take someone into the area of black magic without his knowing what's going on. There are some "Christian" "miracle workers who perform their miracles using kundalini without knowing it, and sometimes they fall into black magic too.
I think you'll probably be okay if you are meditating on good things. That is a sound Christian doctrine.
Philippians 4:8 Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report; if there be any virtue, and if there be any praise, think on these things.
Do not be surprised however if "bad" or "unwanted" thoughts show up. Don't resist them, don't fight them. Just look at them. See them for what they are. Don't feel ashamed or embarrassed by any thought -- just look at it. Some people never see their own ugly thoughts which then continue to brew and stew. Sometimes too, the ugly thoughts aren't really ours but were given to us from other people. Children can have their minds poisoned at times -- and they think the nasty thoughts are their own when really they aren't their thoughts at all.
2 Corinthians 10:5 Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ;
Let the "bad" thoughts finish themselves if they show up while you're trying to meditate peacefully. They'll finish themselves, and then you can say, "No, I don't think so." It can clear out some of the rubbish hiding in our minds.
If you want, I can give you directions on how to use a meditation exercise to purify the heart chakra. I was not a believer in the chakras that much until one day when I was meditating, my heart chakra opened and bloomed like a flower with twelve petals. It really was true then, the human heart has 12 pathways in and out just as the Holy City above does.