Don't worry about it jimma I've been doing digital art and graphics for 5 years now and I've definitely been in a similar situation multiple times. I've felt like I'm not improving and I'll never reach the level that I want to get to. Trust me, keep going and you'll get there. Work big and completely from scratch. Take risks and try things that seem like they're way out of your league. I garauntee you'll improve. Just don't stop