33 LEDs in parallel over-heating unprotected Li-Ion Battery
Ahem... In theory you can add as many LED's as you want, but you MUST add or increase the resistor in series with each LED. 27 ohms sounds good for starters. Beg, borrow or buy a DVM so you can see the current drain from the battery vs. its amp/hour rating. The total current should not exceed 10% of the amp/hour rating, and that lets the LEDs run for ten hours.

LEDs are very efficient so do not be afraid to double the resistor value in series with the LED. They are non-linear devices so that should dim them only slightly, yet save much current drain on the battery.

Be sensible about the total number of LEDs used. The more you add the dimmer each of them will become as you are forced to increase the resistor values.
Red LEDs have the lowest turn-on voltage so use a 33 ohm resistor as a minimum.

If the battery gets hot, measure your current and increase resistor values as needed. You may be close to the maximum number of LEDs you can use already, so double the resistor values to see if that cools the battery down, or limit the number of extra LEDs. There is a finite limit.

Thanks to @TonyStewart for doing the basic math, which shows you are already reaching the batteries limit. Double the resistor values, then check the battery to see if it cools off. I personally would remove some of the extra LEDs, or at least NOT add any more.

A very hot Li-Ion battery is like a small bomb, so go easy on it.