AFAIK, coolant level goes up and down. Pagmainit ang engine, coolant goes up, radiator pushes excess coolant into reserviour. This is done to relive pressure. The radiator gets the coolant form the reserviour when the engine is cool.
when you looked at it was the engine cold or hot? pag cold medyo need mo ng mag add para nasa 3/4 between L and H. pag hot, wag mo muna buksan...hehehe.
Cold po ako nagtse-check. After weekly washing. Ang concern ko lang po talaga bang natural na nababawasan ang coolant over time? Me nagsabi kasi sakin patingin ko raw, me nagsabi naman saking lagyan ko lang ng tubig.
imo, that's not normal. i have a one year old car too, level hasn't changed over the span of one year. maybe if the loss is minimal, like 1 millimeter, then that's ok. i think there's a leak somewhere. check the radiator cap, the leak might be there. there should be some dried up white stuff around it, water/coolant that leaked out when the engine was hot. if you ever decide to refill it, use distilled water mixed with coolant and add to the reservoir, not the radiator. you may also use premixed coolant and simply add. be sure to get the right spec coolant.