<br> is redundant since you need only press the "enter" key to get a line break in your posts. <p> is also largely redundant for the same reason.
Press enter twice and that should leave an empty line between your "paragraphs". Don't forget that when posting, you can click the "Go advanced" button to get more options. Maybe you'll see some stuff you've been missing there.
For example indents.
Using both html and bbcode when one does the job is unnecessary bloat and fluff.