I too began with a 10 lb ball and was still using it at the beginning of last year. I got it through the pro shop at my local bowl at reasonable price and included drilling-took a while for them to find one for me as I wanted a reactive ball. Found however that with this weight could not get consistent hit and carry as the ball would hit the pins and bounce off constantly leaving corner or 5 pin standing. Tried going heavier 11 lb but due to shoulder injury (I thought) could not bowl with heavier weight so put up with it.
Then decided to get some coaching. I got sick of leaving pins on the lane. First session with the coach found I was not holding the ball weight correctly and not putting my thumb in the ball properly which is why I thought I could not use a heavier ball. Took some getting used to but after 12 months am now bowling with a 13lb ball and getting a lot better. So many things to remember now however. The heavier ball is much more consistent and a lot wider choice of balls available.
I have since given my lighter balls to the junior coach to give to juniors ready to step up.
Therefore I would strongly suggest that maybe you find a coach in your area who can help you with the basics of bowling and possibly suggest a ball to suit your style of bowling. I regret not doing it sooner as I spent money on equipment I though I needed rather than on a coach who taught me how to bowl before I bought new equipment.
If you dont need a new ball, I suggest putting a notice on the board at your local centre asking if anyone has a 10 lb ball availalble or ask other league members. Quite often bowlers have balls sitting in the bottom on their cupboards they are willing to give or sell cheaply to beginner bowlers.
Good luck and welcome to the challenge and fun of league bowling and maybe in future years to the big world of tournament bowling or with representative teams in Restricted, Holt or Rachuig Tournaments.