All my girths are too big!?

I have a shetland. He is a little over weight. He is also a stallion. I tried a saddle on him for the first time yesterday and did it again today. Neither girths fit in english or western. So I had to tie a lead line on the girth and wrap it in all kinds of directions. I tried getting on him (which was successful :] ) but then he turned (which I wasn't ready for :[ ) and the saddle slipped off. Luckily I landed on my foot considering I was a foot from the floor and ended up just taking the saddle off and trying . I got on him and sat on him and gave him a lot of pats and he didn't like me sitting on him after a while :/ so I decided to just get off. Are there any small girths like reallly small? English and western?