I am a 21 year old girl dating a 15 year old girl. We have been together for about 5 months now. I have always been wary of her age and the legal consequences that could come about.She will turn 16 in 5 months, which is the legal age of consent in Indiana. However, I did read something about a 4 year age difference. Even with her being of legal age in a couple of months and her parents love us together, could there be other consequences for there being more than a 4 year age difference?

She's not even 16. She has not fully matured mentally and emotionally. I seriously hope her parents are not fond of you two being together (I know mind wouldn't if I dated a 14 year old). That being said, she is not even 16, so she has yet to grow and she could change in terms of her emotional needs and tastes very soon. She may not yet know what she wants and this could backfire unto you.

This just doesn't sound like a healthy relationship.

I agree with not being a healthy relationship. If her parents like the idea, there must be something that they like in you, or maybe something else.
I saw the age difference thing on TV News, where 4 yrs, 4 mo, was an ideal age difference, with the man being older than the woman. I was 10 yrs older than my wife, but she was 23 and I was 33, and we were married 30 yrs.
I really think she is too young for you. She will change her mind many times about many things before she is 18 yrs old! I would start meeting other girls closer to my own age, or at least 18 yrs old now. Good luck.

Yes, if you are 21 and engage in sex with a minor, the crime is elevated to a class B felony

What is the Indiana Legal Age of Consent for 2013? (http://age-of-consent.info/states/Indiana)

Frankly I can't understand parents who would love to have a 21 yr old sexually abuse their child.

Legal age of consent for what? There's no law against dating if the parents agree to it. So I'm assuming you want to know when you can get into her pants? Have you talked to her parents about having sex with their minor child? I doubt they'd be thrilled with you after that conversation.