Life is always best, but it's not bad to look at pictures once in a while too! OR video. People forget to practice their memory-drawing too. Try looking at videos of tigers/ big cats and try drawing from your imagination but also using some of the information you see online.. cause when something's moving, you get to see it in 3D space and understand it better.
Just give it a shot. You have the potential. Keep drawing! Your stuff is already great but you want to take it to the next level so just keep drawing and you'll get it!
Good luck!
Also make it a point to differentiate your animals. A cheetah looks very different from a panther for example. Try to analyze it and see if you can spot the differences in face SHAPE (not colour, etc) but just silhouette or profile of the animal. It'll help. (even I have a tough time too and I've been doing it for a while!)
Just keep going with it but never forget about structure!