
To be honest when I first started out all I ever used was 18 - 70mm that was fine for what I was doing. I didn't buy the 200mm until 2 years ago, so that was 6 years with that other lens and it did me proud. You just have to practise with what you have and have an understanding of how to get the best out of it ( making sure you choose a good bright spot to take pics etc)
Buying bigger lens will not improve your pics... I did at one time buy a cheap 300mm and it was rubbish, too slow to focus, so I got rid quite quickly and stuck with what I knew, until I jumped for the fast 200mm...
get some practise in before you buy any attachments just yet!