Your bonuses on Book of Dead at those stakes is pretty unlucky, yeah! I personally like Book of Dead, it’s a pretty standard game and although it can rinse you for a bonus, it is fair a lot of the time. Millionaire sucks in my opinion, and I’ve never had any luck with Immortal Romance and I used to play it a lot.
Best way to get over a big loss? Have a break from slots for a bit. It’s far too easy to get sucked in and get carried away after a losing session. Take some time off and revisit it again in the future after a short break.
P.s. welcome to the forum!