I speak Urdu (Pakistan) as well as English. I consider myself to be an "English" speaker and Urdu as my second tongue. I often stutter when talking in Urdu. So I have a good English vocabulary and when I get stuck on a word, I can (most times) think of a synonym and say it (I have stopped doing that now). However, sometimes I know the word but just can't seem to remember it, due to being in mid-conversation. It's to do with anxiety or mental blocking I think. So I think a person who doesn't have a lot of practice with English might _actually_ encounter what you are. Just I thought I'd share my experiences and say, hey! Your English is pretty good 👍.bWishing you all the best.