Angela, using one or 2 lb weights ain't nothing abnormal. Women tend to be weak in the upper body, it's very normal. Many of these exercises isolate those upper body muscles and using lower than normal weights (compared to what you'd use for say squats) makes perfect sense. The muscles of your upper body are smaller. When my 6'2", 190lb boyfriend started lifting weights he had to use two pounders for one armed tricep extension and for kickbacks (he'd kill me if he knew I told anyone this, shhhh).

Speaking of tricpes, a really great move to target all 3 heads is the skull crusher/french curl (sometimes called laying tricep extensions), another is the closed grip pench press (with a barbell, should you get yourself one).

Flyes are good exercises, just not for building strength. They are a great stretching move and they really finish off the chest (and the biceps).

Sounds like you're having a blast
Nat