Meditation means spending quality time with 'myself', speaking gently with 'my' mind in a way such that 'I' feel Stillness, Love & Bliss... To experience this stage I need to calm down the chaos / waste. I need to pay gentle attention to the thoughts that I'm creating, & then slowly & consciously channelizing them in the direction of stillness...
Observe this - when your mind is upset, you said you can surrender to God easily. Which means at that time you're consciously deciding to leave all the thoughts behind. This way you're shifting your focus off the problems & then focusing on God. Which is great! This surrendering isn't happening automatically. It is 'you', who is choosing to think only about Him at that time. You successfully put a "full stop" to everything else. The secret lies in the art of channelizing your thoughts in the right direction, which you're doing successfully in this case.
Our mind creates thoughts based on the information (Knowledge) it has, & accordingly it feels. We need to cleanse our mind on a daily basis & feed it with only good, pure & powerful information. God's knowledge (Murli) that we study at Brahma Kumaris is the most elevated food for the mind. RajYoga, that God Himself is teaching, is the only & easy way to connect directly with Him. We recommend you to do the 7 Day RajYoga course at a nearby Brahma Kumaris center (all Godly services are free for everyone).
Once you learn RajYoga Meditation, you'll have amazing self-realization. You'll be able to establish a beautiful relationship with God & have regular conversations directly with Him. Your mind is your property, you're the owner of it! RajYoga teaches us to become the Master of our mind, intellect & senses. No matter how you might be feeling (for an instance - excited / in anxiety), you'll be able to transform it.