Hi lollypop,
So, with your clitoris, it's actually going to be above where your labia are, so them being on the bigger side is unlikely to conceal it from you. If you haven't already seen it, the first illustration in this article makes it really clear where everything is:
Innies & Outies: The Vagina, Clitoris, Uterus and More.
The clitoris can also be harder to find for those with a smaller clitoris, or when someone isn't sexually excited yet. If you're just feeling or looking around at a time when you aren't aroused, it can be harder to find. When a person is aroused, the clitoral hood will retract a bit more, and the clitoral glans (both external portions) will increase a little in size and a lot in sensitivity. If you just feel your way around with your fingers during times like that -- right between the top of the outer labia, and the hood is what connects the inner labia -- it's usually tough to miss because a pretty notable zing is to be felt. Does any of that help?
When it comes to masturbation, there are lots of things you can try. This article offers a really good overview:
Going Solo: The Basics of Masturbation. Too, having difficulty inserting a finger is usually a sign that you're not quite aroused enough for that yet, and/or that you need to add in some more lube.