Nina,
Your distance is tough to assess. There are so many variables involved: age, strength, stamina, athletic experience, discs you throw and amount you play. You will be the best judge of your improvement by seeing your scores drop, remembering how far you threw last time on that hole and how you feel. Comparing your distance to others is like comparing apples to oranges.
Throw lighter plastic that forces YOU to learn how to throw a disc properly, as opposed to the disc doing the work for you. Lighter weights (you picked up on this) in the 150s are a great place to start as are the types of disc you buy. Look for a Valkyrie, Sidewinder or Leopard. These discs will do what you tell them to do. Blizzard plastic is light, but some of the rims are large, which I don't think is advisable to start with them.
Scour YouTube for tutorials. There is no shortage of videos out there. Also, Innova and DiscCraft have throwing tips on their websites.
Practice and watch your game (and distance) improve. It's not always about the long bomb. It's more about consistency, accuracy and placement...and putting! Putting! Putting!
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