It hurts every time i put fingers down there

It's not really necessary to stick your fingers deep inside your vagina to cum, but if you are seeking more intense multiple orgasms then finding and  exploring the G-spot deeper inside is necessary. Why don't you just start with your clit? Locate your clit and gently massage it. Start by taking a relaxing shower or bath, then get into your bed completely naked. Rub your nipples and fantasize. You can also get on the phone and have an erotic conversation. I know a good chat line for this. This should get you turned on and excited, you will be moist or wet, and your clit should swell. This is the perfect time to put more lubrication on middle finger and gently massage. Use lots of lube, get the slippery stuff at the drug store. You may also enjoy a slender dildo that vibrates. 

Sounds like you are very small and tight. Let me know if you need more instruction on where to place your fingers. This is a good start. I can send you a post later and explain the gspot.