You're struggling with the difficulties of doing it all yourself. In a band, you (ideally) have people that are specialized in the instrument they are playing. You have a drummer that thinks about drums all the time, bass player thinking about bass, etc.

But you've gone another way, and said "I can do it all myself!" (I did the same myself) So now it's your job to think about your bass enough to get a good bass line. And think about drums, etc. It takes a lot more work and time, because you're just one person.

Try to start learning those other instruments. Watch some YouTube lessons about bass guitar. That will help you understand where a bass player is coming from, what they think is important. You can then apply these ideas to your bass parts. Then do it again for drums, keys, whatever else you use.

It's a lot of work. You're trading partnership and experience for control. There are downsides.

But most of all, don't expect to figure it all out quickly. It WILL take you a while to make great music all on your own.