Not uncommon.
Don't get discouraged.
1. More models. When I was researching "how to sell models online" it was suggested that you have at least 30 to 50 models in your store when you open. Same as you tho I only uploaded a handful and same as you waited several months before first sale. Once I had over 20 models in my store I would average a couple of sales a month.
2. Diversity. When you get an idea for a model do a search here for it. You may get a thousand results for pixar style lamp. You really have to work at finding things to model no one else has. (fruit loops :) )
3. Patience and Perseverance. Your models look fine, renders are decent with good wire frames . Keep at it and you will do well.