Swiss meringue ercream not being sweet enough? help!?

okay so for the first time i made it woohooo!! i made swiss meringue ercream i was so proud at myself that it came out properlly and it was worth my arm being in pain! the texture was sooo beautifuly smoothh but the only problem is that it wasnt sweet enough =( it tasted like one of those bakery ercreams with noooo sugar in them.. i used the ratio recipe 1.2.3.. 1/2 cup of egg whites 1 cup of sugar and 1 1/2 cups of er... is it possible to add more sugar or will it ruin it? and has everyone ever tried french ercream?.. there is this local bakery the frosting they use sort of tastes like custard but it is made out of er the color is also a bit yellowish thats why i was wondering if it was french buttercream... id really appriciate answers asap! thankkk yooou alll