"Yes, I speak Russian, but only a little"

In the past I have said things like “Да, я говорю по-русски, но только немного.” No one corrected me. Is that also right, or is “немножко” best here? Спасибо большое)))

Your best bet would be to say “но совсем чуть-чуть.” (The “чуть-чуть” part is rendered—more or less—as chew-CHEWT, with the stress on the last syllable.)

No worries. It is perfectly correct to say it like this in Russian. The other options are:
“Да, я чуть-чуть говорю по-русски.”
“Да, я немного говорю по-русски.”
“Да, я немножко говорю по-русски.”
“Да, я говорю по-русски, но только самую малость.”