Well, reading the title of the topic and then onwards that you’re at the level 3 already I was surprised expecting you’d write you’re somewhere at the level 1 or 2. In that stage the people are the most exposed to such things as loosing motivation or even feelling that they’re not going anywhere.
Actually I have nothing to add here but advise you to go through the @AnthonyCusack’s Daily Challenge topic and a cupple of posts written allover the forum by @MarilynHames at least and you’ll surely be motivated again.
Challenge yourself with whatever comes to your mind and try to reach the goal of the forth set challenge but don’t dispare if it wouldn’t come out as you expected. Remember: it’s always another time to do it again and you’ll do every challenge better and better the further you go.
I believe in you so comming this far as to level 3 you have to believe in yourself aswell.
And as always, remember:
“Dysgu Cymraeg
Siarad Cymraeg
Paid â phoeni
a siarad Cymraeg …” 
Hwyl!
Tatjana