From the bank's point of view, you are in negative equity of €83k now.
Your repayments will be higher after you purchase the new house.
The risk to the bank increases quite a bit.
You don't see it this way, but neither did any of the 80,000 or so people who are over 3 months in arrears today.
Even if the bank gives you a negative equity mortgage, you should ask yourselves if this is right for you. You have €75k negative equity now (€83k - €8k savings).
Would you be better off paying down this negative equity as quickly as possible from your savings? If house prices fall you will be delighted. If house prices rise, it's a mixed result. Your negative equity will be eliminated quicker but the cost of a new house will be higher.
If your current house is not suitable for your needs, you should also consider letting it out and renting a more suitable house, although buying is likely to be a much better decision.