Hi Tatyana - thanks for the reply. It's helpful to see the calculation. Let's keep the maths simple!
At around 47-48 North, 00 Pisces is on the MC and 00 Cancer rises. This means that the angle MC-ASC is 120 degrees (DSA - diurnal semi-arc) and angle ASC-IC is 60 degrees (nocturnal semi-arc).
Six equal divisions of the DSA = 20 degrees per division.
Six equal divisions of the NSA = 10 degrees per division.
Now Porphyry makes 3 equal divisions of the same arcs.
So with Porphyry we have three equal divisions of the DSA = 40 degrees per division.
Three equal divisions of the NSA = 20 degrees per division.
Now Porphyry cusps are:
H1 = 00 Cancer
H2 = 20 Cancer
H3 = 10 Leo
H4 = 00 Virgo
H5 = 10 Libra
H6 = 20 Scorpio
H7 = 00 Capricorn
H8 = 20 Capricorn
H9 = 10 Aquarius
H10 = 00 Pisces
H11 = 10 Aries
H12 = 20 Taurus
Your cusps are:
H1 = 10 Gemini
H2 = 10 Cancer
H3 = 00 Leo
H4 = 20 Leo
H5 = 20 Virgo
H6 = 00 Scorpio
H7 = 10 Sagittarius
H8 = 10 Capricorn
H9 = 00 Aquarius
H10 = 20 Aquarius
H11 = 20 Pisces
H12 = 00 Taurus
Now midpoint Porphyry houses:
H1 = 00 Cancer (10 Cancer)
H2 = 20 Cancer (00 Leo)
H3 = 10 Leo (20 Leo)
H4 = 00 Virgo (20 Virgo)
H5 = 10 Libra (00 Scorpio)
H6 = 20 Scorpio (10 Sagittarius)
H7 = 00 Capricorn (10 Capricorn)
H8 = 20 Capricorn (00 Aquarius)
H9 = 10 Aquarius (20 Aquarius)
H10 = 00 Pisces (20 Pisces)
H11 = 10 Aries (00 Taurus)
H12 = 20 Taurus (10 Gemini)
Please do check my calculations and accept my apologies if I have not fully understood your reasoning. However, I think it is very likely that the 'cusps' you have been using are the midpoints of the Porphyry houses.
The following chart is cast for the approximate latitude that gives the cusps above in Porphyry.

The following chart is cast for the same latitude with Sripati.

I think Chris is right that you have been using Sripati cusps which are the midpoints of the Porphyry houses.
I hope that helps. Thanks for your interest in Planetdance.
Ed