A really fast thesaurus... with lots of synonyms.
Other words for happy include content, cheerful, glad, elated, jubilant, and ecstatic — choose one to match how strong the feeling is, from quietly pleased to overjoyed.
For intense joy use elated, jubilant, ecstatic, or overjoyed — each is far stronger than "happy". For everyday cheer, cheerful, glad, or pleased fit better.
Elated, ecstatic, jubilant, euphoric, and overjoyed all mean very happy, so you can drop the "very" and use one vivid word instead.