"...too"

'I too know only very little about that.'
Group too and only close to the words they determine.

I only know very little about that too = that is another subject that I know very little about.
I too ['also' sounds better to my ear] know very little about that = I am another person who knows very little about...

When modifying with only and also, the modifying word should go as close the the word as possible, to avoid confusion.

Ah I see. Thanks Marius Hancu.

PBF

Thanks Philip for your help.

PBF

Hi PBF

The use of 'too' is OK, and I would not call the sentence "incorrect". However, I'd also say that the construction of this particular sentence is not one that you're likely to hear terribly often.