I keep getting different definitions for an equilibrium.
Hard to comment not seeing the context of each thing you listed. First of all, I would not call them definitions (perhaps with the exclusion of the last one), they are just describing behavior of the system at equilibrium.
If the system is at equilibrium, it doesn't change in time, or the changes are not changing the system state.
I've read that it's the same proportion of reactants and products
If the system doesn't change, proportion stays constant. Doesn't mean if the proportion stays constant, system is at equilibrium.
I've read that it's the same ratio of reactants and products
How is it different from the previous statement? Are ratio and proportion two different things? Can one change and the other stay constant?
I've read that it's the same amount of reactants and products
If the system doesn't change, amounts stay constant.
I've read that it's the same concentration of reactants and products
If the system doesn't change, concentrations stay constant.
and I've read that it's the same rate of forward and reverse reactions.
This one is slightly different - it describes how the system stays unchanged. As the forward and backward reaction proceed at the same speed, neither amount nor concentration of the substances present change. How much is consumed is also produced, and the net effect is zero.
I don't know the differences (...) between proportions, ratios, amounts, concentrations, and rates.
If you don't know what these thing mean, you have no chance of understanding why all the statements you have listed can describe the same situation. However, don't blame scientists for that - you can't understand the definition when it uses notions that you don't understand. If I will tell you an abelian group is - by definition - a commutative group, you would have still no idea what I am talking about - but it is hardly my fault.
You have to start at the very beginning - proportions and ratios are not chemistry, more like a basic algebra. Amount, concentration and reaction rate are definitely chemistry, but I bet they were introduced to the class earlier.