I think you're doing just fine.

Look carefully at the words you've used here...

Within a few weeks of trying manifesting, my requests miraculously were answered. After a while I found no joy in what had appeared.

Look at the difference between the first sentence above and the second sentence.

Unless these sentences are not representative of your true feelings, the first suggests to me some considerable joy in what you received...miraculously is not a word most people use in this context to signify unhappiness :)

But the key phrase to me lies in the second sentence...where you said: "after a while".

What does this mean?

Basically this...you've manifested what you've wanted (and you were happy about it) and now after a while you have launched some new desires from that new place of having manifested that stuff.

Nothing wrong here at all...this is what life is about...having constant new desires!

So certainly no reason to feel within yourself that you've done something wrong. You've done just fine. You've just temporarily forgotten that you'll never have it all perfect...there will always be something else you will want.

As Vesuvius implied, the joy is in the journey, not the destination. See the poem Ithaca.

Regarding your question about whether you should add For My Highest Good...sure, you can...if it makes you feel better.

Remember there is nothing magic about any phrase like this. The Universe doesn't speak English or whatever your primary language is. It doesn't care what words you use. The Universe responds only to your vibrational offering, which is indicated by how you feel.

So if adding that phrase makes you feel better, use it...or any other phrase that makes you feel better...or even no extra phrases at all, if that instead makes you feel better.

There is more joy and satisfaction in the seeking than the obtaining. Or, to put it another way, it is the journey, not the destination, that is most important.

Human beings are designed this way, to be striving, not standing still. Once you obtain a goal, you should immediately set a new one.

But I certainly think that "for the highest good" is a good way to live, and I think you will feel a greater sense of accomplishment if you do so.

I always say (or say internally) "for the highest good of all concerned....." that way I know what happens is for the best for myself and anyone else associated with the issue. I have no worries about imposing my will on anyone else. This has worked well for me, for many years!

When I put my desires in God's hands I know it will be for my highest good. My manifesting comes from recognition. I see everything that comes to me that I want and thank God for it.

It builds trust that God is a great provider for me. All I need is a desire for something and it comes.

This is a constant and consistent life experience, so much so that I often feel like, "God what more wonderful blessings do you have for me?" I then simply let God answer that, I don't ponder it. I just let it go as if I was talking to anyone else.

When I put it in God's hands, I needn't worry about goofing up my manifestation because it is not my manifestation, it is God's blessing.