I'm finally trying to start a career, and I need help making beats

I've always wanted to try doing music, but never actually did it, sometimes I used to try rapping something off my mind and that's it, but recently I've been really trying to get better and maybe drop a couple of songs (or at least record them so I can listen to them later).

Now, I figured I should also start trying to make my own beats, as I feel like that would give me more room to improve my overall skills (also, I have no money to pay for beats). I got a few ideas and I'm using bandlab to make the beats, but I'm really struggling with it.

I've made a couple of drum patterns, but the melodies always end up being a problem for me, do you guys have any tips? I've watched some YouTube videos and it has helped me, but whenever I make a melody, it always sounds wrong/off. I've made some melodies that I liked at first, but as I worked on the song, they all started to sound really bad, as if the melody was never good to begin with.

I'm already using a scale and doing chord progressions, so I don't believe that's the problem, I just can't turn it into good melodies, would appreciate any help.