Bob, make sure your fly line weight rating is matched to your rod, if your rod is marked as 7, then it will need a #7 line to load it, in other words, to make it cast easily. If the rod says 7/8 then the 8 weight line will work better for you. Otherwise the rod will feel sloppy or "dead" when you try to cast. And that means you will fight against it to get a decent cast. And casting should be relaxed and easy, not a battle. Your rod will work when it is casting the line it is designed for. The same as trying to cast light float tackle a long way., you need the weight for the job. Diawa and Shakespeare and most brands make good value rods to get you fishing and match your cash and are great value. Your Sensor rod needs the matching line rating to make it work.
You say it is very flexible at the tip, that sounds if you are going too fast, trying too hard. Slow down a bit. Let the rod do the work, I will try and find you some casting links to look at (Help from some FM guys here please)
If you can find the money to get some professional casting lessons then you will be amazed at how much you can learn. Well worth it, but dont despair if you cannot afford it. Find a friendly fishery (ask around) and most folk will be happy to give advise and tips, most will be good. And a friendly tackle shop is a good starter too(go in when they are not busy) and ask them for advise. They will be glad to get a new customer.
Enjoy your fishing and get ready for the help that will arrive for you on this site when they all come back from their fishing or barbecues. Have fun.