Can a thumb size girth like 3" (which is much below than average size of 4.5-5") is enough for women ? i have heard girth matters a lot?

Girth: Girth is the measurement around the middle of something, especially a person's waist. In the case of the penis, 3 inches around may be smaller than normal. Girth and size-Length of the penis, is purely a personal factor in a woman's sexual pleasure desires. Some say, it is not the size of the wand, but the magic in it. If you know how to satisfy a woman with what you got, she most likely will not mind. If she is fixated on size, you could use toys as foreplay.

Size: can matter, although, too large can be a problem. Technique and other things such as foreplay can help stimulate and excite women, don't give up! Best of luck.