Welcome to Gaia! ::

If I may make a couple suggestions on the message/finer points of it.

ええ、かっこよかったよ。(remember that the word かっこいい functions the same as いい, something I was also admittedly slow to, at first)

色々なかわいい物を買えてうれしかった。 クーキーもとてもおいしかった。 (much like English, the subtleties in tone are very important to consider, much like changing the 2 letters separating can't and won't totally changes the intended message behind a statement).

The rest of the changes I'd like to make are just more finnicky nitpicking, so I'll leave them as is, and add that I agree with his advice. From the tone of your intent, it seems like this person means a great deal to you, and YOU should the one to write this message, not us. It's hard when it's in a language you don't know much of yet, but it says a lot more when your hands write the message, and not someone else's.

When someone else gets involved, it could send a message completely different from the one you wanted you convey to this person. Ultimately, people have a way of telling who wrote the message they got and when it's not who the person says it is, and this kind of thing is never beneficial to anyone in the long run. I firmly believe if you want to show yourself to this person, then you will do so in your own words, not someone else's interpretation of them.