My girlfriends' daughter

My girlfriends' daughter likes me to tickle her back. When she was 10 it was innocent but now shes' 14 and I look forward to it. Her mom works nights so we never see her anymore. We're alone most nights and have gotten pretty close. We have a ritual, we each take a shower and get into our pajamas. She gets me a beer and gets herself a coke. We turn the tv on and I sit on the couch. She lies across my lap with her head on a big pillow and her sweet pussy on my lap. I've learned not to wear underwear and I've noticed she doesn't either. We pull her top up around her neck and I lightly tickle her back. I do this for a while and she gets very relaxed. I touch the sides of her breasts and she tells me It feels nice. I always get an erection and press it against her pussy. Lately I "accidently" have taken my hard dick out of my pajamas and she rocks her pelvis on it. She always leaves her flannel bottoms on and this is always done outside her clothes. Sometimes she'll raise her body up so I can feel her breasts and play with her nipples. She tells me she likes when I do that. A couple of times she positioned my dick between her legs and rocked up and down while I squeezed her pretty ass. Both times I shot my load on her ass. She'll pull down her top and then fall asleep. She likes it and I like it but we don"t talk about it. She'll do this without my asking her, she wants to do it. Even in front of her mom she'll lie on my lap but of course not with all the touching. I know its wrong but I've never forced her and I truly think she loves being with me.