The worrying thing about your post...as implied by Robin...is the absence of comment on your instructor's view.
Your sporadic training may be a factor, but many people do the same and make somewhat quicker progress. If you are stuck or struggling on a particular aspect of your flying, or on several aspects, your instructor would surely have let you know what the problems are, and given you strategy's for overcoming them.
If this hasn't happened (which I would find hard to believe) your alarm bells (re the quality of training you are getting) should be clanging loudly.
I am NOT implying this is case; I'm merely suggesting, your debriefs should be covering your problems and adressing possible solutions. I would have thought a short burst of concentrated training would have been a reasonable starting point?????