It's said, even in more orthodox tantras like the Lakshmi Tantra that the Goddess comes to you in the form that means the most. Not eveyone has the best and most fantastic relationship with their mother. Sister's usually okay, but mostly friends. Friends, nice. But she will also come as a lover, if that's your need.
Tantra though is not about believing in God and Goddess outside of oneself. You are developing love and it is erotic today while you are young and full of hormones, and later that will subside a bit when you get older. It makes little dfference. This is your bhava. And together with Goddess you are a bhavani. What will be most important is if you understand that the devata, all of them, are components of your own mind. It's easier to do puja if you see them as separate. but they are not separate from you.
You think of you as your body perhaps. When you see yourself more as your mind, then the differences make less meaning than the compatibility. Also this having a relationship with Devi inside does a lot to get rid of loneliness, and also makes one a more compassionate lover in the material world.
The tantra is really for the life. The life is not for the tantra. Or both are for both. The Sri Vidya is the knowledge of all goodness. Shri is goodness.
Now in this school we do a lot of practice on Matangi, and she is about love and friendship, the best friend you can have. She is less erotic sentiment, and more friendly. Swamiji said she is the way to win Lalita's heart.
Kamakhya is Lalita. Kurukulla is also Lalita. These and Meenakshi are very direct paths to the heart of the Goddess. But not as thorough as Sri Vidya, which the path outlined by Parasurama's Kalpa Sutras gives step by step worship in order to gain entire fullness of a relationship with Devi.
It's a complex path, and takes some years to get ones mind wrapped around. But it is the path of the Goddess and is perfect in every way.
If you see it all though as worshipping within the mind and there being no within or without then many questions will go away.