Hello everyone , new member here so I salute every one of you
Okay , well I'm self-taught guitar player (well pretty begginer) so I'm not able to get any education from a musician at the moment , and I'm trying to learn as much as I can in music theory.So far I've got stuck in a one topic that drives me crazy because I just cant understand or cant comprehend it somehow.
What do I do is I'm trying to find the melody in that I hear in my head and I try to figure it out in chord shapes well not in the usual chord shapes we use often.I try to explore in different frets...

So lets say I've found a good sounding chord that I dont even know what it is , I find the chord and move on I thought I'm in the key but I'm wrong I'm terrible at it..

So I try to start from scratch I try to go from the first chord I've found but I cant create any progession because I cant find what key I'm in so I cant go from that point.Therefore I dont have any roadmap to create what I want to hear...

Here a very basic idea that I had with a good strumming pattern .
Here it is ;

I strum this first chord and then add one note to create a melody of course with a strumming pattern I had but its not important here , what important is I want to know what can I do with this and how can I figure out key signature :

D# 9(no 3rd)/C# 6add9(no 5th) //// D# sus2/A# sus4
---6--- ---6---
---6--- ---6---
---6--- ---8---
---8---- ---8---
---6---- ---6---
---x---- ---x---

D# 7 and then C# sus2/G# sus4
---6--- ---4---
---8--- ---4---
---6--- ---6---
---8---- ---6---
---6---- ---4---
---x---- ---x---

D sus2/A sus4

Okay this is kind of my progression that I had heard in my head but I feel like something wrong and as I dont have any roadmap to figure out the rest of the details what am I supposed to do from now on..What's best way figure out this theory so that I can finally write music properly.My intention is mostly exploring different approach to chords so that I can create melody and a good progression but it comes really hard to me when I try to do that because I dont know exactly to find out key signatures...

Okay lastly I have another question about circle of fifths and sharps and minor chords...So lets say I have D# (kind of obsessed with this chord) , how can I use effectively to find out the key signature from this circle of fifths..

I know its pretty long read but I dont have any musician person that I know to ask , so hopefully someone would explain it very clearly .Thank you in advance.
I would start with learning major and natural minor scales. From there you can use the circle of fifths to figure out the minor, major, and diminished chords for that key.

E.g. in a major scale the root, 4th, and 5th are major. 2nd, 3rd, 6th minor. And 7th diminished. In minor the root, 4th, 5th are minor. 3rd, 6th and 7th major. And the 2nd diminished.

Suspended chords are usually used to create suspense. Where they best fit will probably depend on the song, but you would usually use them and then move to a chord that releases the tension in the listeners ears.