If you are aware that some of your behavior stems from trying to compensate for your own lost motherhood ability to provide, then the behavior is not too healthy. There is always the possibility that a person may start to resent the one that always helps them even when they do not ask for help. In a way it may cause ego injury where the person being helped feels inferior or feels obligated in some way to their helper. It may make her feel controlled in a way.
Money does not equate with love. If you can, offer to babysit or help her in the house instead ex: making dinner for them, watching the baby while she goes out, etc.
Instead, you may want to put aside some money each month for a college fund or the grandkid's first car one day. Buying things and showing affection are all wonderful but everything usually is done within limits except loving (that does not cost money). That way you also respect the autonomy of your daughter and her family.