So, what you want to do is carry another creature with misty step.
Summary: the rules are not perfectly clear, although a reasonable interpretation suggests you cannot carry another creature, see below for details. An issue you bring up is what about clothes and equipment, Sage Advice clarifies that, see below for details. Having said all that, work with your DM -- if it is ambiguous enough to come here looking for answers, it's ambiguous enough to get on the same page with your DM.
Compare with Dimension Door, for instance
Dimension Door provides additional guidance for what you can carry:
You can bring along objects as long as their weight doesn't exceed what you can carry. You can also bring one willing creature of your size or smaller who is carrying gear up to its carrying capacity. The creature must be within 5 feet of you when you cast this spell.
Misty Step provides no such additional information.
What about clothes and equipment?
The Sage Advice Compendium says this about Misty Step:
Misty step doesn’t say the caster can bring worn or carried equipment with them. Are they intended to leave everything, including their clothes, behind?
No, the caster’s worn and carried equipment are intended to go with them. (misty step)
"Worn and carried equipment" seems pretty clear to me.
Is a range of "self" important?
Maybe? But just looking at three teleportation spells, misty step, dimension door, and teleport, their ranges are inconsistent one compared to another. Misty step has a range that refers to who can teleport, as does the teleport spell, but dimension door doesn't.
Is that an argument to support that misty step only teleports the caster? Or is it an inconsistency that doesn't really help determine whether misty step can include a passenger or not? Up to interpretation, but I think the latter.
What matters is your game
Teleporting in its many forms can be tricky. The rules often lack specificity, and that's okay.
To me, it seems pretty clear that the spell does not include carrying another person, but that's an interpretation. The spell doesn't say. And really, the rules aren't so well written that pointing to things like dimension door and "range of self" are really 100% conclusive.
What's more important is that the DM and the players are on the same page.
My best advice . . . get with your DM. Express your concerns and thoughts. Come up with an interpretation that works for your table. The rules are just a shortcut to an understanding between the players (including the DM). Given that the rules are not perfectly clear, a conversation is warranted. Whether misty step allows you to carry someone or not is less important than whether you and the DM agree to how it works.