first of all, it's summer so start wearing lose shorts so your erections will be obvious. second start going over when you know you will have plenty of time to play. next time offer her a massage, this will show her you don't just care about your own enjoyment, even if that's all you really care about it'll still help to make her think you care about making it good for her to. if she says ok, get her to lay down again and straddle her so your groin is pressed against her ass, this way when you get hard she will know it. then start massaging her shoulders and slowly make you way down her back. after that suggest she take her top off cause it'll feel better. then start from the shoulders again, but this time as you get to her back, let your hands run down her side a bit just enough so the tips of your fingers touch the side of her breast. after that figure out the rest.
not to hard when you put the girls needs first. women do like nice guys who put them first, they just don't want you to be a pansy about it and wait for permission all the time.