I have married Aela but also use her as a follower. But when she follows me i cant find an option to trade with her. Is there anyway to give her weapons and armour?

If that's the case, it's not the end of the world, there are other good archer followers. But as an answer to the actual question, I wouldn't know.

You can, but she has to follow you first. You may be confused with extra options there are in dialogue after the marriage. The option to open her inventory is second to last I think.
If you already have her follow you and the option doesn't appear, try dismissing her and then tell her to follow you again.