Newly self-employed: How to maximize retirement/401k contributions

Hi all.

Just as the title suggests. I’m recently self-employed from June 2025. I was W2 via my ex-employer through April and took some time off before kickstarting the new venture.

I’m typically on top of investments. Here’s a current breakdown of retirement accounts:

1. Roth IRA - Schwab (2025 contribution done via backdoor Roth conversion)
2. Employer 401k - Empower (2025 contribution partially done; roughly $6k)

Currently, I have sent in documents/forms to Schwab to open an individual 401k. I am thinking of transferring my Empower 401k (ex-employer). Need to figure that out if it’s the right move.

For 2026 Roth IRA, I’ll do the same which is lump sum in January for max contribution (I think $7500(?)) via backdoor conversion as will be over MAGI. Can I do more here…?

For 401k… this is where I’m struggling. Any tips would be useful. Is Schwab the best option for me? Can I do over the normal $23.500 limit?

Thanks in advance!