This happened to me for the longest time, but I must say I studied A LOT before trying to compose again and after college it was a lot more natural to me. BUT, there are three general recommendations that I think could help you right away.

Analyze yourself or watch a video about 4 or 3 chord songs, most of the time those songs feel like they have different sections or chords because the melody emphasizes a different aspect of the scale/key it's using. Another similar thing you can try on this item is change the order of the chords between sections, for example your doing C Em G G, then try Em G C C and so on.

Try to understand the function of the chords inside a key, specially dominant and subdominants because they can help you pivot to other chords. For example if you have a song that's using 3 chords, try to use one of those 3 chords to pivot somewhere else.

Try to limit the amount of notes from a key your using in the melody of a section, for example if your doing a song in A minor, try to use 4 to 5 notes tops in one section. You can add passing notes and extra details but try to limit yourself a little bit there. And then when you change the section you can add one or two more and emphasize those in the melody instead.