I know exactly how you feel, airgirl. I've had exactly the same problems with being less than confident when it comes to flying solo (or just good honest caution as some would call it).
Don't let yourself get anxious about going solo, it is not a hurdle to overcome but simply a natural next step that you will know when you will feel ready for. Continue to practice landings in all sorts of conditions and general aircraft handling skills, you won't be wasting money at all, it will all go into that bank on experience inside your head. also get your instructor to give you a taste of what you'll be doing post 1st solo such as a dual trip to another airfield. Then when the time is right for you and the weather is good you will be just itching to get rid of that instructor for a while.
Keep us posted on on how you get on.