Is it normal for a 3 months old baby to drool a lot? I thought babies only drool when they are teething?

Yes drooling is v common. Teeth can appear as early as 3 months but here is a long long time of drooling - maybe a month before the teeth really appears

Kids now are a little different. My #3 & #4 started drooling ard 3 mths old too Even after performing the 4th mth thingy, also the same. Lol

Yes, it's normal. Teething not necessarily must have teeth. The gums so needs to prepare itself for teeth growth too.